Home » Pharmaceutical Glossary » Glossary of Terms - H

Hairpin
A double helical region formed by base pairing between adjacent (inverted) complementary sequences in a single strand of RNA or DNA.

Haloenzyme
An enzyme that contains a non-protein component.

Halogen
One of the chlorine group (bromine, chlorine, fluorine, iodine) of elements, all univalent; they form monobasic acids with hydrogen, and their hydroxides (fluorine forms none) are monobasic acids. The radioactive element, astatine, also belongs to the halogen group.

Halophile
An organism that displays accelerated growth or is dependent on high salt concentrations.

Handshake
Requires the recipient of an electronic data record to acknowledge to the sender that the record has been received.

Handwritten Signature
The scripted name or legal mark of an individual handwritten by that individual and executed or adopted with the present intention to authenticate a writing in a permanent form. The act of signing with a writing or marking instrument such as a pen or stylus is preserved. The scripted name or legal mark, while conventionally applied to paper, may also be applied to other devices that capture the name or mark. (also see:

Haploid
A single set of chromosomes (half the full set of genetic material), present in the egg and sperm cells of animals and in the egg and pollen cells of plants. Human beings have 23 chromosomes in their reproductive cells.

Hardness
Concentration of calcium and magnesium salts in water. Hardness originally referred to the soap-consuming power of water; as such it is sometimes also taken to include iron and manganese. "Permanent hardness" also known as "noncarbonated hardness " is the excess of hardness over alkalinity. "Temporary hardness" also known as "carbonated hardness" is equal or less than the alkalinity. Permanent hardness can cause boiler or pipe scale and failure of reverse osmosis membranes.

Harvesting
The separation of cells from growth media. It can be accomplished by filtration, precipitation, or centrifugation.

Hazardous Chemical Reaction
A reaction which generates pressure or byproducts which could cause injury, illness or harm to humans, domestic animals, livestock or wildlife.

Hazardous Occupancy - Group H - (California Building Code)
Group H occupancies include buildings or structures, or portions thereof, that involve the manufacturing, processing, generation or storage of materials that constitute a high fire, explosion, or health hazard. There are eight divisions in this Group:

1. Division 1 - Occupancies with a quantity of material in the building exceeding regulation set limits and that present a high explosion hazard, such as blasting agents, fireworks, black powder, certain oxidizers and detonatable unstable (reactive) materials, and other materials (refer to Code for more details).

2. Division 2 - Occupancies where combustible dust is manufactured, used, or generated in such a manner that concentrations and conditions creates fire or explosion potential, or occupancies where materials exceeding regulation set limits present a moderate explosion hazard or a hazard from accelerated burning, such as some organic peroxides, pyrophoric gases, flammable or oxidizing gases, some nondetonatable unstable (reactive) materials, and other materials (refer to Code for more details).

3. Division 3 - Occupancies where flammable solids, other than combustible dust, are manufactured, used or generated, or occupancies where materials exceeding regulation set limits present a high physical hazard, such as some organic peroxides and oxidizers, pyrophoric liquids or solids, flammable solids in storage, flammable or oxidizing cryogenic fluids, and other materials (refer to Code for more details).

4. Division 4 - Repair garages not classified as Group S, Division 3 Occupancies.

5. Division 5 - Aircraft repair hangars not classified as Group S, Division 5 Occupancies, and heliports.

6. Division 6 - Semiconductor fabrication facilities and comparable research and development areas in which hazardous production materials (HPM) are used and the aggregate quantity of materials exceeds those set by regulations. Such facilities and areas shall be designed and constructed following a different set of regulations.

7. Division 7 - Occupancies having quantities of materials in excess of those set by regulations, and that are health hazards, such as corrosives (except stationary lead-acid battery systems), toxic and highly toxic materials, irritants, sensitizers, and other health hazards (refer to Code).

8. Division 8 - Laboratories and similar areas used for scientific experimentation or research having quantities of materials not in excess of those set by regulations, and not otherwise classified as Group B, Division 2 Occupancies (refer to Code for more details).

Hazardous Substance
A substance which by reason of being explosive, flammable, toxic, poisonous, corrosive, oxidizing, irritant or otherwise harmful, is likely to cause injury.

Haze
The abnormal appearance of a localized diminishing in brightness or luster of a surface when compared to the adjacent surfaces.

Health Hazard
Classification of a chemical for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur in exposed persons. The term "health hazard" includes chemicals that are carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents that act on the hematopoietic system, and agents that damage the lungs, skin, eyes or mucous membranes.

Heat
A form of energy associated with the motion of atoms or molecules in solids and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation. Two important characteristics of heat are:

1. Heat cannot be destroyed, only transferred from on body to another, or converted to another form of energy.

2. Heat always flows from the warmer to the colder substance.

Heat Affected Zone (HAZ)
That portion of the base metal that has not been melted but whose microstructure or mechanical properties have been altered by the heat of welding, brazing, soldering, forming, or cutting.

Heat Labile
Able to be destroyed or altered by high temperature. Heat labile pharmaceuticals are sterilized by filtration.

Heat Number
An alphanumeric identification of a stated tonnage of metal obtained from a continuous melting in a foundry furnace.

Heat of Vaporization
The amount of heat needed to change a unit volume from a liquid to a vapor at a given pressure without a temperature change.

Heavy Metals
High molecular weight metal ions, such as lead. Known for their interference with many processes, and "poisoning" of catalysts, membranes, and resins.

HeLa Cells
An established line of human cervical carcinoma cells used to study the biochemistry and genetics of human cell growth.

Helix
A spiral, staircase-like, structure with a repeating pattern described by two simultaneous operations, rotation, and translation. It is the natural conformation of many biological polymers.

Hematin
An iron protoporphyrin differing from heme in that the central iron atom is in the ferric (Fe+++) rather than the ferrous (Fe++) state; the prosthetic group of methemoglobin.

Hematopoietic


Heme


Hemoglobin
The red, respiratory conjugated protein of erythrocytes, consisting of approximately 6 percent heme and 94 percent globin (a protein).

Hemophilia
A hereditary, plasma-coagulation disorder, principally affecting males but transmitted by females, and characterized by excessive, sometimes spontaneous, bleeding.

Hemopoietic
Pertaining to or related to the formation of blood cells.

HEPA (High Efficiency Particulate Air) Filters
Filters with a minimum efficiency of 99.97% for 0.3µm particle size as determined by test. The test can be by the monodispersed dioctyl phthalate (DOP) method or other equally sensitive method. When operated at design velocity, larger and smaller particles are captured at higher efficiencies. HEPA filters are made of compressed and bonded micro-fiberglass or Teflon® corrugated to produce a high surface area in a small area panel of filter medium. Employed in unidirectional airflow benches, air handlers, and as terminal air supply filters in cleanrooms.

Heparin
A sulphur containing polysaccharide that stops blood from clotting by preventing the conversion of prothrombin to thrombin and by neutralizing thrombin. It is contained in the mast cells and is extractable from various tissues, notably the lung.

Hepatotoxin
A toxin that is destructive to parenchymal (specific tissue) cells of the liver.

Heredity
Transfer of genetic information from parent cells to progeny.

Heterotrophs
One of two categories in which microorganisms are classified on the basis of their carbon source. Heterotrophs use organic compounds such as carbohydrates, lipids, and hydrocarbons as a carbon and energy source.

Heterozygosity
The presence of different alleles at one or more loci on homologous chromosomes.

High Purity Process Systems
The equipment that includes the stainless steel vessels, tube, pipe, fittings, and valves used to manufacture and transport drug products.

Hold-up Volume
The volume of liquid remaining in a vessel or piping system after it has been allowed to drain.

Hollow Fiber
Refers to reverse osmosis and ultrafiltration membranes formed into small diameter (about 0.05" I.D.) tubes. The inner surface is a very thin (RO or UF) membrane skin supported by a thicker porous outer layer that gives the tube its strength. Hollow fibers are used in bundles of 1,000 or more in a single cartridge shell. Water is forced through the center (upstream surface) of each tube and purified permeate is collected from the outer wall (downstream surface).

Homeobox
A short stretch of nucleotides whose base sequence is virtually identical in all the genes that contains it. It has been found in many organisms from fruit flies to human beings. In the fruit fly, a homeobox appears to determine when particular groups of genes are expressed during development.

Homologous Chromosome
Chromosome containing the same linear gene sequences as another, each derived from one parent.

Homology
Similarity in DNA or protein sequences between individuals of the same species or among different species.

Hormone
A type of chemical messenger, occurring both in plants and animals, that acts to inhibit or excite metabolic activities. Its site of production is distant from the site of biological activity.

Host Vector (HV) System
The host is the organism into which a gene from another organism is transplanted. The guest gene is carried by a vector, which is a larger DNA molecule, such as a plasmid, or a virus into which that gene is genetically engineered and which then propagates in the host. NIH Guidelines under Appendix E. - Certified Host-Vector Systems contains a list of derivatives host-vector systems previously classified as Host-Vector 1 Systems or Host-Vector 2 Systems, they are: Bacillus subtilis, Saccharomyces Cerevisiae, Escherichia coli, Neurospora crassa, Streptomyces, and Pseudonomas putida. (also see:

HPLC (High Pressure Liquid Chromatography)
Sometimes called high-performance liquid chromatography, is a separation technique based on a solid stationary phase and a liquid mobile phase. Separations (into distinct bands) are achieved by partition, adsorption, or ion-exchange processes, depending upon the type of stationary phase used. Each band is then profiled as the solvent flows through a UV detector, or by fluorescence, or refractive index detectors.

HSA (Human Serum Albumin)
The main protein constituent of human serum. It has no prosthetic group and is soluble in water and dilute salt solution. It is sometimes used in the treatment of shock, hypoproteinemia, and erythroblastosis fetalis.

Human Gene Therapy
Insertion of normal DNA directly into cells to correct a genetic defect.

Human Genome
The full collection of genes needed to produce a human being.

Human Genome Initiative
Collective name for several projects begun in 1986 by DOE to:

1. Create an ordered set of DNA segments from known chromosomal locations.

2. Develop new computational methods for analyzing genetic map and DNA sequence.

3. Develop new techniques and instruments for detecting and analyzing DNA.

This DOE initiative is now known as the Human Genome Program. The national effort, led by DOE and NIH, is known as the Human Genome Project.

Human Genome Project


Humidity Ratio


Huntington's Disease
An adult-onset disease characterized by progressive mental and physical deterioration; it is caused by an inherited dominant gene mutation.

Hybrid Systems
Combination of electronic and paper records, common in today's analytical labs, in which raw data is recorded electronically to reconstruct the analysis, but the final results are printed and signed on paper. FDA does not prohibit hybrid systems but has expressed some concerns about their usefulness.

Hybridization
The process of joining two complementary strands of DNA or one each of DNA and RNA to form a double-stranded molecule.

Hybridoma
A hybrid cell resulting from the fusion of a specific antibody producing spleen cell with a myeloma cell. The hybrid cell has the growth characteristics of the myeloma component and the antibody secreting characteristics of the spleen cell and will multiply to become a source of large quantities of pure, monoclonal antibody.

Hydrogen Peroxide (H2O2)
A colorless, heavy, strongly oxidizing, unstable liquid used principally in aqueous solutions as an antiseptic, bleaching agent, oxidizing agent, and laboratory reagent. In the vapor phase, as an airborne sterilant.

Hydrolysis
A chemical reaction between water and organic compounds, particularly esters, ketones, and alcohols. This reaction can lead to breakdown of some proteins.

Hydrophilic
Having a strong affinity for water. Its opposite, hydrophobic.

Hydrophobic
Non-wetting; water repelling.

Hydrotest
A pressure test of piping, pressure vessels, or pressure-containing parts, usually performed by pressurizing the internal volume with water at a pressure determined by the applicable code or to test the integrity of a process system.

Hygienic
Of, or pertaining to, equipment and piping systems that by design, materials of construction, and operation provide for the maintenance of cleanliness (pyrogen free but not sterile) so that products produced by these systems will not adversely affect human or animal health.

Hygienic Clamp Joint
A tube outside diameter union consisting of two neutered ferrules having flat faces with a concentric groove and mating gasket that is secured with a clamp, providing a nonprotruding, recessless product contact surface. Tri-clamp™ is a Tri-Clover proprietary name; consequently, it should not be used to describe the above-mentioned fitting unless that particular brand is used.

Hygroscopicity
The affinity for absorbing water.

Hypochlorite
A weak, unstable salt of hypochlorous acid used in aqueous solutions as a bleach, oxidizer, deodorant, and disinfectant.