Macrophage: large mononuclear phagocyte. This cell may be called a histiocyte in the tissues; it is called a monocyte in the blood. An antigen must come in contact with or pass through a macrophage before it can become a processed antigen with the ability to encounter the then sensitize a small lymphocyte.
Macrophage-Activating Factor: sensitized T lymphocytes can release a non-specific macrophage-activating factor that creates a cytotoxic population of macrophages that appear to distinguish malignant from normal cells, killing only malignant ones.
Macrorestriction Map: map depicting the order of and distance between sites at which restriction enzymes cleave chromosomes.
Major Histocompatibility Complex (MHC): a cluster of genes encoding cell surface molecules that are polymorphic within a species and that code for antigens, which leads to rapid graft rejection between members of a single species that differ at these loci. Several classes of protein, such as MHC class I and class II proteins, are encoded in this region.
Malformation: also congenital anomaly or birth defect. Any defect present at birth, probably of developmental origin.
Managed Care: the use of a "manager" to control utilization of medical services and control costs.
Managed Competition: government regulation of a health care market which uses competition as the means to achieve efficiency objectives within a framework of government intervention designed to achieve other policy objectives, such as equity.
Management: the measures taken to plan, organize, operate and evaluate all the many elements of a system and the personnel involved.
Manual Vacuum Aspiration (MVA): a technique for evacuating the contents of the uterus through use of a specially designed hand-held syringe.
Mapping: see -- gene mapping, linkage map, physical map.
Mapping Population: the group of related organisms used in constructing a genetic map.
Marginal Benefit: the additional benefit obtained by consuming the last (or next) unit of a commodity.
Marker: see -- genetic marker.
Market Failure: the situation in which a market economy fails to attain economic efficiency.
Market Mechanism: the interaction of buyers and sellers in market and mixed economies which determines the nature and volume of goods and services produced and their distribution.
Mass Spectrometry: an instrument used to identify chemicals in a substance by their mass and charge.
Maternal Mortality Ratio, Reported: the quotient between the number of maternal deaths in a given year and the number of live births in that same year, expressed by 100,000 live births, for a given country, territory, or geographic area, as reported from the national health authority. Maternal death is defined as the death of a woman while pregnant or within the 42 days after termination of that pregnancy, regardless of the length and site of the pregnancy, due to any cause related to or aggravated by the pregnancy itself or its care but not due to accidental or incidental causes.
Mean: the average of a sample of observations.
Mean Value: the average of a set of numbers. In epidemiology, the sample mean is the average value of the observations in a sample.
Meatus: opening to the urethra.
Median: the middle value when the values are arranged in order from the smallest to the largest.
Median Value: the median is a number that separates the upper 50% of a sample from the lower 50%. It is the middle value of a distribution.
Medical Eligibility Criteria: criteria for a woman's eligibility to use a contraceptive method, based on the relative health risks and benefits of using such a method for a woman with a given condition.
Medical Savings Account: allows or mandates people to place money in (tax-free) savings accounts to be used only for medical expenses, usually in conjunction with the purchase of a catastrophic stop-loss health insurance plan.
Megabase (Mb): unit of length for DNA fragments equal to 1 million nucleotides and roughly equal to 1 cM. See also -- centimorgan.
Meiosis: the process of two consecutive cell divisions in the diploid progenitors of sex cells. Meiosis results in four rather than two daughter cells, each with a haploid set of chromosomes. See also -- mitosis.
Memory Cells: cells that can mount an accelerated antibody response to antigen.
Mendelian Inheritance: one method in which genetic traits are passed from parents to offspring. Named for Gregor Mendel, who first studied and recognized the existence of genes and this method of inheritance. See also -- autosomal dominant, recessive gene, sex-linked.
Messenger RNA (mRNA): RNA that serves as a template for protein synthesis. The mature form of processed RNA used as a template for directing translation of proteins. See also -- genetic code.
Meta-analysis: an amalgamation of studies -- a complex task to avoid misleading conclusions. The goal of combining results from different sources is to delineate which features are universal. The quality of the studies included is important to the final result. Many think that only prospective randomized clinical trials should be combined for a meta-analysis because such trials are usually of the highest quality.
Metaphase: a stage in mitosis or meiosis during which the chromosomes are aligned along the equatorial plane of the cell.
Methylation: (see DNA Methylation).
MeV: 1,000,000 eV.
MHC Restriction: the ability of T lymphocytes to respond only when they are presented with the appropriate antigen to which in association with either self MHC class I or class II molecules.
Microarray: sets of miniaturized chemical reaction areas that may also be used to test DNA fragments, antibodies, or proteins.
Microbial Genetics: the study of genes and gene function in bacteria, archaea, and other microorganisms. Often used in research in the fields of bioremediation, alternative energy, and disease prevention. See also -- model organisms, biotechnology, bioremediation.
Microinjection: a technique for introducing a solution of DNA into a cell using a fine microcapillary pipet.
Microinjection (of Sperm): injection of one or more sperm under the outer covering of the oocyte for fertilization.
Micronuclei: chromosome fragments that are not incorporated into the nucleus at cell division.
Micturition: another term for urination or voiding.
Migration Inhibition Factor: a lymphokine produced when a sensitized lymphocyte is exposed to an antigen to which it is sensitized. Migration inhibition factor inhibits the migration of these lymphocytes.
Milking: checking for penile discharge by placing the fingers of one hand several centimeters behind the scrotum and bringing them upward and forward towards the base of the penis.
Minimum Data Set (MDS): federally mandated screening and assessment form for Medicare- and Medicaid-certified long-term care facilities in the United States. This form is completed within 14 days of admission to the facility, quarterly, and when there is a significant change in the resident's status. An annual update is also required. The information collected in the MDS is used in planning the care of the individual.
Minor Histocompatibility Antigens: these antigens, encoded outside the MHC, are numerous but do not generate rapid graft rejection or primary responses of T cells in vitro. They do not serve as restricting elements in cell interactions.
Missense: a mutation that alters a codon so that it encodes a different amino acid.
Mitochondrial DNA: the genetic material found in mitochondria, the organelles that generate energy for the cell. Not inherited in the same fashion as nucleic DNA. See also cell, DNA, genome, nucleus.
Mitochondrial Inheritance: mitochondria are inherited exclusively from women. Because they contain DNA, mitochondrial inheritance allows transmission of genes directly from the woman to her offspring.
Mitogen: a substance that induces immunocompetent lymphocytes to undergo blast transformation, mitosis, and cell division (causing mitosis or cell division).
Mitosis: the process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell. See also -- meiosis.
Mixed Formulae: often payment of professionals is based on a mix of methods (i.e. capitation plus fee-for-service for some services). Similarly, systems can be supplemented by bonus/target payments as an incentive for achieving certain objectives.
Mixed Urinary Incontinence: combination of involuntary leakage associated with urgency and also with exertion, effort, sneezing, and coughing. A person has both urge and stress urinary incontinence.
Mobilization: one of three sub-functions in the financing of health systems which aims at identifying and getting the money required to meet the health needs of the people, individually and collectively, in a given health system.
Models: simplified descriptions of processes or systems.
Model Organisms: a laboratory animal or other organism useful for research.
Modeling: the use of statistical analysis, computer analysis, or model organisms to predict outcomes of research.
Molecular Biology: the study of the structure, function, and makeup of biologically important molecules.
Molecular Farming: the development of transgenic animals to produce human proteins for medical use.
Molecular Genetics: the study of macromolecules important in biological inheritance.
Molecular Medicine: the treatment of injury or disease at the molecular level. Examples include the use of DNA-based diagnostic tests or medicine derived from DNA sequence information.
Monitoring: the ongoing process of collecting and analyzing information about the implementation of the activity such as newborn resuscitation.
Monitoring and Evaluation: monitoring is the process of keeping track of events. For example, the monitoring of a project may involve counting the number of people coming into contact with it over a period of time or recording the way in which the project is administered and developed. Evaluation involves making a judgment as to how successful (or otherwise) a project has been, with success commonly being measured as the extent to which the project has met its original objectives. Both the "process" (activities) and "outcomes" (what is produced, for example in terms of changes in the health of those targeted by the project) can be monitored and evaluated.
Monoclonal Antibody: antibodies with such high intrinsic specificity that only one or two antigenic determinants are recognized.
Monogenic Disorder: a disorder caused by mutation of a single gene. See also -- mutation, polygenic disorder.
Monogenic Inheritance: see -- monogenic disorder.
Monokines: soluble substances, secreted by monocytes, that have a variety of effects on other cells.
Monosomy: possessing only one copy of a particular chromosome instead of the normal two copies. See also -- cell, chromosome, gene expression, trisomy.
Moral Hazard: The possibility of consumers or providers exploiting a benefit system unduly to the detriment or disadvantage of other consumers, providers or the financing community as a whole, without having to bear the financial consequences or their behavior in part or in full.
Morbidity: a state of disease.
Morbid Map: a diagram showing the chromosomal location of genes associated with disease.
Morula: a compact sphere of 16 blastomeres that forms at about 3-4 days after fertilization.
Morbidity Rate: illness or disability rate, usually expressed per 1000 population.
Mortality Rate: death rate per defined population, usually expressed per 1000.
Mortality Rate from Land Transport Accidents, Estimated: the estimated total number deaths from land transport accidents, in the total population or of a given sex and/or age, divided by the total number of this population, expressed per 100,000 population, for a given year, in a given country, territory, or geographic area. Underlying causes of death grouped under this heading are those ICD-10 codes V01-V89.
Mortality Rate from Motor Vehicle Traffic Accidents, Estimated: the estimated total number deaths from motor vehicle traffic accidents, in the total population or of a given sex and/or age, divided by the total number of this population, expressed per 100,000 population, for a given year, in a given country, territory, or geographic area. Underlying causes of death grouped under this heading are those under ICD-9 codes E810-E819 or ICD-10 codes V02-V04(.1-.9), V09.2,V09.3,V12-V14(.3-.6), V19(.4-.6),V20-V28(.3-.9), V29-V78(.4-.9),V80(.3-.5), V81.1,V82.1,V83-V86(.0-.3), V87(.0-.8),V89.2,V89.9.
Mosaic: an individual composed of two or more genetically dissimilar cell lines but from the same species. This can come about by somatic mutation or by grafting cells between individuals of close genetic constitution, such as dizygotic twins.
Mosaicism: the presence of two or more populations of cells with different characteristics within one tissue or organ.
Mother-To-Child Transmission (MTCT): transmission of HIV from an infected mother to her infant during pregnancy, labor or after delivery through breast milk.
Mouse Model: see -- model organisms.
Multicenter Trial: a single trial conducted according to a single protocol but at more than one site (from ICH E6). These sites may be across multiple countries. They are advantageous because they offer more rapid patient accrual and allow for greater protocol complexity. Multicenter trials reduce the opportunity for an individual's bias to influence the conduct of the trial; they increase the likelihood for the inclusion of a more representative study population and facilitate a higher standard for data processing and analysis.
Multidisciplinary: HIA is not the preserve of any one disciplinary group. Instead, it draws on the experience and expertise of a wide range of "stakeholders", who are involved throughout the process. These may include professionals with knowledge relevant to the issues being addressed, key decision makers, relevant voluntary organizations and -- perhaps most importantly -- representatives of the communities whose lives will be affected by the policy (Barnes and Scott-Samuel, 1999).
Multifactorial Inheritance: inheritance of traits that are determined by a combination of genetic and environmental factors.
Multifactorial or Multigenic Disorder: see -- polygenic disorder.
Multiplexing: a laboratory approach that performs multiple sets of reactions in parallel (simultaneously); greatly increasing speed and throughput.
Multistage Sampling: a multistage sample is an extension of a cluster sample, where the initial clusters are broken into further smaller clusters. Once a final selection of clusters to sample is made, a proportion of the subjects within each cluster is sampled. (e.g. if the sampling frame was an entire country then the country would be broken down into regions, then these regions would be broken down into cities and towns and then these would be randomly sampled).
Multivariate Analysis: a technique of analysis of data that factors many variables. A mathematical model is constructed that simultaneously determines the effect of one variable while evaluating the effect of other factors that may have an influence on the variable being tested. The two most common algorithms developed to accomplish this task are the step-up and stop-down procedure. Variables are added to an initial small set or deleted from an initial large set while testing repeatedly to see which new factor makes a statistical contribution to the overall model.
Murine: organism in the genus Mus. A rat or mouse.
Mutagen: an agent that causes a permanent genetic change in a cell. Does not include changes occurring during normal genetic recombination.
Mutagenicity: the capacity of a chemical or physical agent to cause permanent genetic alterations. See also -- somatic cell genetic mutation.
Mutation: an alteration of DNA sequencing in a gene those results in a heritable change in protein structure or function that frequently has adverse effects. Any heritable change in DNA sequence. See also -- polymorphism.
Myc Proto-Oncogenes: the proto-oncogene family that includes c-myc, N-myc, L-myc, and R-myc. They encode nuclear-associated DNA-binding proteins that affect DNA replication and transcription.
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