BIOSENSORS (CHEMICAL), BIOCHIPS, OLIGONUCLE-

OTIDE, OLIGONUCLEOTIDE PROBES, MALDI-TOF-MS,

ASSAY, MICROARRAY (TESTING).

Hybridoma The cell line produced by fusing a myeloma (tumor cell) with a lymphocyte (which makes antibodies); it continues indefinitely to express the immunoglobulins (antibodies) of both parent cells. See also

MONOCLONAL ANTIBODY (MAb), AGING.

Hydrazine A chemical with formula N2H4. Used as a rocket fuel, and in the hydrazinolysis of glycoproteins. See also HYDRAZINOLY-

SIS (OF GLYCOPROTEINS, TO ISOLATE UNREDUCED

OGLIOSACCHARIDE SIDE CHAINS), GLYCOPROTEIN,

REDUCTION (IN A CHEMICAL REACTION).

Hydrazinolysis (of glycoproteins to isolate unreduced oligosaccharide side chains) A technique that used the chemical hydrazine to separate and isolate the oligosaccharide portion from the protein portion of a glycoprotein. The hydrazine chemically “chews up” the polypeptide (i.e., protein) portion of a glycoprotein molecule, leaving the intact oligosaccharides behind. It can subsequently be analyzed (after chromatographic separation from the peptide pieces and other chemical components). See also REDUCTION

(IN A CHEMICAL REACTION), HF CLEAVAGE,

P O L Y P E P T I D E (P R O T E I N ), G L Y C O P R O T E I N ,

SEQUENCING (OF OLIGOSACCHARIDES), HYDRA-

ZINE, CHROMATOGRAPHY.

Hydrofluoric Acid Cleavage See HF CLEAVAGE.

Hydrogenation A chemical reaction/process in which hydrogen atoms are added to molecules (e.g., of unsaturated fatty acids) in edible oils. In the case of fatty acids, the fraction of each isomeric form (trans vs. cis fatty acids) and the molecular chain length (of the fatty acids present) have a large impact on the melting characteristics of each (fat or oil), with shorter-chain fats melting at lower temperature.

Hydrogenation is the most common chemical reaction utilized in the edible oils (processing) industry. Hydrogenation increases the solids (i.e., crystalline fat) content of edible fats/oils, and improves their resistance to thermal and atmospheric oxidation (e.g., for frying of foods). Those increases in solids and resistance to oxidation result from the reduction in the fat/oil relative unsaturation, plus

increased geometric and positional isomeriza-
tion of the fat/oil molecules. The edible oil/fat
hydrogenation reaction is accomplished by
treating fats/oils with pressurized hydrogen
gas in the presence of a catalyst. As a result,
the (usually) liquid oils are converted to more-
saturated fats, which are semisolids at an
ambient temperature of 72°F (22°C).
The presence of trans fatty acids in
hydrogenated edible oils can be reduced sig-
nificantly via changes in catalyst, tempera-
ture, pressure, etc. used in the hydrogenation
reaction. In general, natural oils and fats pos-
sessing melting points lower than 121°F
(50°C) are nearly completely absorbed in the	H
digestive system of typical humans. See also
FATTY ACID, MONOUNSATURATED FATS, SATU-
RATED FATTY ACIDS, DEHYDROGENATION, ESSEN-
T I A L F A T T Y A C I D S , L A U R A T E , L E C I T H I N ,
TRIGLYCERIDES, UNSATURATED FATTY ACID, SOY-
BEAN OIL, CONJUGATED LINOLEIC ACID (CLA),
OXIDATION, ISOMER, STEREOISOMERS, CATALYST,
SUBSTRATE (CHEMICAL), TRANS FATTY ACIDS.
Hydrolysis Literally, means “cleaved by
water.” It is used for a chemical reaction in
which the chemical bond attaching an atom,
or group of atoms to the (rest of the) mole-
cule is cleaved, followed by attachment of a
hydrogen atom at the same chemical bond.
Hydrolytic Cleavage A chemical reaction in
which a portion (e.g., an atom or a group of
atoms) of a molecule is “cut” off the mole-
cule via hydrolysis. See also HYDROLYSIS.
Hydrolyze To “cut” a chemical bond (i.e., with
a molecule) via hydrolysis. See also HYDROL-
YSIS.
Hydrophilic This term means water loving or
having a great affinity for water. It is used to
describe molecules or portions of molecules
that have an affinity for water. The property
of having an affinity for water at an oil-water
interface. For example, ordinary sugar that
dissolves readily in water is said to be hydro-
philic (i.e., a molecule that is “water loving”).
See also AMPHIPHILIC MOLECULES.
Hydrophobic This term means water hating or
having a great dislike for water. It is used to
describe molecules or portions of molecules
that have very little or no affinity for water.
The property of having an affinity for oil
(nonpolar environments) at an oil-water

© 2002 by CRC Press LLC

interface. For example, a nonpolar hydrocarbon such as butane (as used in lighters) that will not dissolve in water, but which will dissolve (be miscible) in oil is said to be hydrophobic (i.e., a molecule that is “water

hating”). See also AMPHIPHILIC MOLECULES.

Hydroxylation Reaction A chemical reaction in which one or more hydroxyl groups (i.e., the -OH group) is introduced (i.e., is chemically attached) to a molecule.

Hyperacute Rejection See GRAFT-VERSUS-HOST

DISEASE (GVHD).

Hyperchromicity The increase in optical density that occurs when DNA is denatured. See

Halso DEOXYRIBONUCLEIC ACID (DNA), DENA-, ( ).

TURED DNA OPTICAL DENSITY OD

Hypersensitive Response A protective/defensive response by certain plants to “infection” by plant pathogens (bacteria, fungi, etc.), in which those plant cells that are immediately adjacent (to the infected area of plant) are “instructed” to self-destruct via apoptosis, in order to cordon off the infected area (to prevent further spread of the infection). The initiation of the hypersensitive response is often triggered by signaling molecules that are produced by the pathogens themselves. For example, one particular protein produced by the soil fungus triggers a hypersensitive response that often is so severe that the entire plant dies. See also PATHOGENESIS

RELATED PROTEINS, PROTEIN, PATHOGEN, BACTERIA, FUNGUS, CELL, APOPTOSIS, SIGNALING, SIG-

NALING MOLECULE.

Hyperthermophilic (organisms) See also

THERMOPHILE, THERMOPHILIC BACTERIA.

Hypostasis Interaction between nonallelic genes in which one gene will not be expressed in the presence of a second. See

also EPISTASIS, GENE, EXPRESS, ALLELE.

Hypothalamus A part of the brain structure, lying near the base of the brain, it regulates a number of hormones. As a part of the brain, it constantly receives (neurochemical) signals from nerve cells (neurons). The hypothalamus monitors those signals, and converts them into hormonal signals [e.g., it generates a “burst” of hormones in response to certain visual stimuli, certain physical (e.g., sexual) stimuli, etc.]. Also, the hypothalamus is able to monitor and detect changes in the blood levels of hormones coming from endocrine glands. For example, the metabolic hormone insulin (from the pancreas) and the reproductive hormone estrogen (from the ovaries) both trigger changes in function in the hypothalamus.

The hypothalamus regulates biological processes (metabolic rate, appetite, etc.). A major function of the hypothalamus is to control reproduction, via secretion of gona- dotropin-releasing hormone (GnRH) from the tips of hypothalamic nerve fibers that extend downward toward (into) the pituitary gland. Similarly, the hypothalamus also helps to control the body’s growth (from birth until the end of puberty) via secretion of growth hormone-releasing factor (GHRF) to the pituitary gland. See also HORMONE,

ENDOCRINE HORMONES, ENDOCRINE GLANDS,

ENDOCRINOLOGY, PITUITARY GLAND, GROWTH

HORMONE (GH), NEUROTRANSMITTER, GROWTH

HORMONE-RELEASING FACTOR (GHRF).

© 2002 by CRC Press LLC

I

IBA See INDUSTRIAL BIOTECHNOLOGY ASSOCIATION.

IBG See INTERNATIONAL BIOTECHNOLOGY GROUP.

ICAM Intercellular adhesion molecule. See

also ADHESION MOLECULE.

IDA Acronym for Iron Deficiency Anemia.

See also IRON DEFICIENCY ANEMIA (IDA).

IDE “Investigational Device Exemption” application to the Food and Drug Administration (FDA) seeking approval to begin clinical studies of a new medical device.

Ideal Protein Concept Refers to the protein content in the feed ration (food) eaten by livestock and poultry (and humans). Feed that contains ideal protein contains protein(s) that — when digested by an animal — yields all of the essential amino acids, in proper proportions, for the growth and/or maintenance needs of that animal. “Ideal protein” varies for different species (e.g., pigs require different amino acids/rations than chickens do). “Ideal protein” varies for different stages in the life of a given animal (e.g., poultry require more sulfur-containing amino acids, such as methionine, during life stages when feather growth is at a comparatively high rate). The animal’s requirement for one essential amino acid is proportionally linked to the animal’s requirements for another. Increasing the supply (when deficient) of one essential amino acid in the animal’s diet would improve that animal’s (growth) performance if no other amino acids were limiting. Feed rations formulated to contain “ideal protein” have been shown to reduce the amount of nitrogen (nitrates) excreted by livestock and poultry, by as much as 50%.

See also AMINO ACID, PROTEIN, ESSENTIAL AMINO ACIDS, ESSENTIAL NUTRIENTS, METHIONINE (met),

DIGESTION (WITHIN ORGANISMS), SOY PROTEIN,

HIGH-LYSINE CORN, HIGH-METHIONINE CORN.

0-8493-XXXX-X/01/$0.00+$1.50 © 2001 by CRC Press LLC

Idiotype The region of the antibody molecule
that enables each antibody to recognize a spe-
cific foreign structure (i.e., epitope or hapten)
is said to have an idiotype (for that epitope
or hapten). An identifying characteristic (or
property) of the epitope or hapten that one is
talking about. See also EPITOPE, HAPTEN, ANTI-
GEN, ANTIBODY, CATALYTIC ANTIBODY.
IDM See INTEGRATED DISEASE MANAGEMENT.	I
IFBC See INTERNATIONAL FOOD BIOTECHNOLOGY
COUNCIL.
IFN-Alpha Alpha interferon. See also INTER-
FERONS.
IFN-Beta Beta interferon. See also INTERFERONS.
IGF-1 See INSULIN-LIKE GROWTH FACTOR-1.
IGF-2 See INSULIN-LIKE GROWTH FACTOR-2.
IGF-I See INSULIN-LIKE GROWTH FACTOR-1.
IGF-II See INSULIN-LIKE GROWTH FACTOR-2.
IL-1 See INTERLEUKIN-1.
IL-Ira See INTERLEUKIN-1 RECEPTOR ANTAGONIST.
Immune Response See C E L L U L A R I M M U N E
RESPONSE, ANTIBODY, HUMORAL IMMUNITY.
Immunoassay The use of antibodies to iden-
tify and quantify (measure) substances by a
variety of methods. The binding of antibod-
ies to antigen (substance being measured) is
often followed by tracers, such as fluores-
cence or (radioactive) radioisotopes, to
enable measurement of the substance. See
also ANTIBODY, TRACER (RADIOACTIVE ISOTOPIC
METHOD), ANTIGEN, ELISA, RADIOIMMUNOASSAY,
ASSAY, EIA, FLUORESCENCE, NEAR-INFRARED
SPECTROSCOPY (NIR).
Immunoconjugate A molecule that has been
formed by attachment to each of two origi-
nally different molecules. One of these is
generally an antibody; hence, the word
“immunoconjugate.” Classic organic drug
molecules such as methotrexate, adriamycin
chlorambucil, etc.; radionuclides; enzymes;

© 2002 by CRC Press LLC

toxins; and ribosome-inhibiting proteins may be conjugated to antibodies. The salient point is that the antibody portion of the conjugate is there to “steer” the biologically active molecule to its target. See also CONJU-

GATE, “MAGIC BULLET”, ANTIBODY, MAGNETIC

PARTICLES.

Immunocontraception Any process or procedure in which an organism’s immune system is utilized to attack or inactivate the reproductive cells (e.g., sperm) within the organ-

ism. See also CELLULAR IMMUNE RESPONSE,

ANTIBODY, HUMORAL IMMUNITY, GERM CELL.

Immunogen See ANTIGEN.

Immunoglobulin (IgA, IgE, IgG, and IgM) A class of (blood) serum proteins representing

Iantibodies. Often used, along with the more specific monoclonal antibodies, in health diagnostic reagents. In certain people genetically predisposed to foodborne allergies, immuno- globulin-E (IgE) initiates an immune system response to antigen(s) present on protein molecule(s) in the particular food to which that

person is allergic. Severe allergic reactions to foods may lead to death. See also PROTEIN,

ANTIGEN, ALLERGIES (FOODBORNE), ANTIBODY,

IMMUNOASSAY, B LYMPHOCYTES.

Immunosuppressive That which suppresses the immune system response (e.g., certain chemicals). See also CELLULAR IMMUNE

RESPONSE, HUMORAL IMMUNITY.

Immunotoxin A conjugate formed by attaching a toxic molecule (e.g., ricin) to an agent of the immune system (e.g., a monoclonal antibody), that is specific for the pathogen or tumor to be killed. The immune system-agent portion (of the conjugate) delivers the toxic chemical directly to the specified (disease) site, thus sparing other healthy tissues from the effect of the toxin. See also RICIN, MONO-

CLONAL ANTIBODIES (MAb), “MAGIC BULLET”.

Imprinting A cellular process in which certain genes within an organism’s cells are “disabled” during the earliest stage(s) of the organism’s development. For example, the embryo of a female mammal (which receives two copies of the X chromosome — one from each parent) disables one of those copies, at random, in each of its cells, so the female becomes a genetic mixture of its two

parents. See also CELL, GENE, CHROMOSOMES,

X CHROMOSOME.

In Silico See IN SILICO BIOLOGY.

In Silico Biology A set of computer modeling technologies, via which researchers can:

1.Create computer models of specific cells to

a.see how a given disease impacts that cell

b.see how a given pharmaceutical impacts that cell

2.Create computer models of specific organs to

a.see how a given disease impacts that organ

b.see how a given pharmaceutical impacts that organ

3.Create computer models of specific organisms to

a.see how a given disease impacts that organism

b.see how a given pharmaceutical then impacts that disease within that organism

4.Create computer models of specific organisms that possess a given genome to

a.see how a given disease impacts that specific organism/phenotype to

b.see how a given pharmaceutical then impacts that disease within that organism/phenotype

5.Create computer models of protein “digestion” (i.e., breaking apart into constituent peptides), for comparison with the actual peptides (fragments) that are determined (e.g., via MALDI- TOF-MS) to have resulted from chemical digestion of those protein molecules (e.g., via immersion in trypsin).

See also RATIONAL DRUG DESIGN, RECEPTOR MAPPING, CELL, BIOCHIPS, GENOME, GENOMICS,

PHARMACOGENOMICS, PROTEIN, PROTEOMICS,

PHENOTYPE, MALDI-TOF-MS, PEPTIDE, TRYPSIN.

In Silico Screening A set of computer modeling technologies via which researchers can (vicariously) screen chemical compounds for their potential as pharmaceutical candidate compounds, pesticide candidate compounds, etc. The chemical compounds are

© 2002 by CRC Press LLC