Human Chorionic Gonadotrophin: From 3 Different Sources
See gonadotrophin, human chorionic.
A glycoprotein hormone secreted by the PLACENTA in early pregnancy, and stimulating the CORPUS LUTEUM within the ovary (see OVARIES) to secrete OESTROGENS, PROGESTERONE, and relaxin. The hormone is essential for the maintenance of pregnancy up to about 6–8 weeks of gestation. A RADIOIMMUNOASSAY can be used to detect its presence, and pregnancy can be diagnosed as early as six days after conception by testing for it in the urine. Some tumours also secrete human chorionic gonadotrophin, particularly HYDATIDIFORM MOLE, which produces large amounts.
(hCG) a hormone, similar to the pituitary *gonadotrophins, that is produced by the placenta during pregnancy. hCG maintains the secretion of *progesterone by the corpus luteum of the ovary, the secretion of pituitary gonadotrophins being blocked during pregnancy. Large amounts are excreted in the urine, and this is used as the basis for most *pregnancy tests. Serum hCG monitoring is used for tracking early pregnancy and detecting *ectopic pregnancies (in which the level will not double over a 48-hour period, as it does with normal pregnancies). The level of hCG in the serum is also one of the indicators used in *prenatal screening tests: levels are higher in pregnancies affected by Down’s syndrome in comparison with normal pregnancies (see also papp-a; triple test). Levels of hCG are very high in *gestational trophoblastic neoplasia. Some malignant tumours (e.g. malignant teratoma, choriocarcinoma, endodermal sinus tumour) secrete hCG, which can be used as a *tumour marker. A preparation of hCG is given by injection to treat fertility problems due to ovulation disorders and to induce *superovulation in in vitro fertilization.
In simple terms, this is the genetic recipe for making a human being. GENOME is a combination of the words gene and chromosome, and a genome is de?ned as all the genetic material – known as deoxyribonucleic acid, or DNA – in a cell. Most genes encode sequences of AMINO ACIDS, the constituents of proteins, thus initiating and controlling the replication of an organism. The identi?cation and characterisation of the human genetic puzzle have been a key bioscience research target. The Human Genome Project was launched in 1990 (and completed in 2003) to produce a full sequence of the three million base pairs that make up the human genome.
Carried out as two separate exercises – one by a privately funded American team; another by an international joint venture between tax-funded American laboratories, a charitably funded British one and several other smaller research teams from around the world – the ?rst results were announced on 26 June 2000. In February 2001 the privately funded American group, known as Celera Genomics, announced that it had identi?ed 26,558 genes. At the same time the Human Genome Project consortium reported that it had identi?ed 31,000. Allowing for margins of error, this gives a ?gure much lower than the 100,000 or more human genes previously forecast by scientists. Interestingly, genes were found to make up only 3 per cent of the human genome. The remaining 97 per cent of the genome comprises non-coding DNA which, though not involved in producing the protein-initiating genetic activity, does have signi?cant roles in the structure, function and evolution of the genome.
One surprise from the Project so far is that the genetic di?erences between humans and other species seem much smaller than previously expected. For example, the Celera team found that people have only 300 genes that mice do not have; yet, the common ancestor of mice and men probably lived 100 million years or more in the past. Mice and humans, however, have around twice as many genes as the humble fruit ?y.
Cells die out when they become redundant during embryonic development: genes also die out during evolution, according to evidence from the Genome Project – a ?nding that supports the constant evolutionary changes apparent in living things; the Darwinian concept of survival of the ?ttest.
Apart from expanding our scienti?c knowledge, the new information – and promise of much more as the Genome Project continues – should enhance and expand the use of genetic engineering in the prevention and cure of disease. Studies are in progress on the gene for a receptor protein in the brain which will shed light on how the important neurotransmitter SEROTONIN in the brain works, and this, for example, should help the development of better drugs for the treatment of DEPRESSION. Another gene has been found that is relevant to the development of ASTHMA and yet another that is involved in the production of amyloid, a complex protein which is deposited in excessive amounts in both DOWN’S (DOWN) SYNDROME and ALZHEIMER’S DISEASE.... human genome
A method of diagnosing genetic abnormalities in a fetus using a small sample of tissue taken from the chorionic villi at edge of the placenta. Because the cells have the same chromosome makeup as those in the fetus, they can be used to detect genetic abnormalities. Chorionic villus sampling (CVS) is usually performed in the first 3 months of pregnancy in women who are at a higher-than-normal risk of having a child with a chromosomal disorder, such as Down’s syndrome, or a genetic disease, such as thalassaemia. Chromosome analysis of the villi cells takes place in the laboratory. CVS slightly increases the risk of miscarriage. choroid A layer of tissue at the back of the eye, behind the retina. The choroid contains many blood vessels that supply nutrients and oxygen to the retinal cells and to surrounding tissues in the eye. choroiditis Inflammation of the choroid. It is often caused by infections such as toxocariasis or toxoplasmosis, more rarely by sarcoidosis, syphilis, and histoplasmosis. It sometimes has no obvious cause. Treatment includes corticosteroid drugs for the inflammation, and antibiotic drugs for any causative infection.... chorionic villus sampling
... chorionic gonadotrophic
Gonadotrophins, or gonadotrophic hormones, are hormones that control the activity of the gonads (i.e. the testes and ovaries). In the male they stimulate the secretion of TESTOSTERONE and the production of spermatozoa (see SPERMATOZOON); in the female they stimulate the production of ova (see OVUM) and the secretion of OESTROGENS and PROGESTERONE. There are two gonadotrophins produced by the PITUITARY GLAND. CHORIONIC GONADOTROPHIC HORMONE is produced in the PLACENTA and excreted in the urine.... gonadotrophins
The name of the causative agent of AIDS.... hiv (human immunodeficiency virus)
Human skills and capabilities generated by investments in education and health.... human capital
A composite index that measures the overall achievements in a country in three basic dimensions of human development— longevity, knowledge and a decent standard of living. It is measured by life expectancy, educational attainment and adjusted income per capita in purchasing power parity (PPP) US dollars. The HDI is a summary, not a comprehensive measure of human development.... human development index (hdi)
See ASSISTED CONCEPTION.... human fertilisation & embryology act 1990
See ASSISTED CONCEPTION.... human fertilisation & embryology authority (hfea)
See AIDS/HIV.... human immunodeficiency virus
See HLA SYSTEM.... human leucocyte antigen (hla)
UK legislation that lays down the framework and rules governing organ transplantation. The UK Transplant Support Service Authority (UKTSSA), a special health authority set up in 1991, is responsible for administering the NHS Organ Donor Registry and the Act (see APPENDIX 7: STATUTORY ORGANISATIONS).... human organs transplants act
The study of the interrelationships between humans, the tools they use, and the environment in which they live and work.... human-factor research
Creutzfeldt-Jakob disease. See: BOVINE SPONGIFORM ENCEPHALOPATHY. ... mad-cow disease, human
Wounds caused by one person biting another. Human bites rarely cause serious tissue damage or blood loss, but infection is likely, particularly if the bite is deep. There is a risk of tetanus infection. Transmission of hepatitis B, herpes simplex, and AIDS by a bite is a theoretical hazard.... bites, human
The complete set of human genetic material. The human genome consists of 23 chromosomes, which, together, contain about 30,000 genes. All body cells contain 2 sets of the 23 chromosomes, one set inherited from the father and the other from the mother. An international research programme, the Human Genome Project, was launched in 1990 with the aim of identifying all the human genes. The first rough draft of the project was published in 2000.... genome, human
Hormones that stimulate cell activity in the ovaries and testes. Gonadotrophins are essential for fertility. The two most important gonadotrophins are follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which are secreted by the pituitary gland. Another gonadotrophin, HCG (see gonadotrophin, human chorionic), is produced by the placenta during pregnancy. Certain gonadotrophins are used as drugs in the treatment of infertility.... gonadotrophin hormones
A hormone produced by the placenta in early pregnancy. Human chorionic gonadotrophin (HCG) stimulates the ovaries to produce oestrogen and progesterone, which are needed for a healthy pregnancy. HCG is excreted in the urine, and its presence in urine is the basis of pregnancy tests on urine samples. ... gonadotrophin, human chorionic
(HLA) A type of protein belonging to the group known as histocompatibility antigens, which play a role in the immune system.... human leukocyte antigen
(HHS) the major US government agency providing health care. The department was created in 1953 and assumed its current name in 1980. HHS administers more than 300 health and health-related programmes and services, including *Medicare and *Medicaid. Other activities include research, immunization services, and providing financial assistance for low-income families. Almost a quarter of federal spending occurs through HHS.... department of health and human services
a nondepartmental public body set up in 2007 to promote human rights and equality in regard to age, disability, gender, race, religion and belief, pregnancy and maternity, marriage and civil partnership, sexual orientation, and human rights. It replaced the Commission for Racial Equality, the Disability Rights Commission, and the Equal Opportunities Commission.... equality and human rights commission
(gonadotrophic hormone) n. any of several hormones synthesized and released by the pituitary gland that act on the testes or ovaries (gonads) to promote production of sex hormones and either sperm or ova. Their production is controlled by *gonadotrophin-releasing hormone. The main gonadotrophins are *follicle-stimulating hormone and *luteinizing hormone. They may be given by injection to treat infertility. See also human chorionic gonadotrophin.... gonadotrophin
(GnRH, gonadorelin) a peptide hormone produced in the hypothalamus and transported via the bloodstream to the pituitary gland, where it controls the synthesis and release of pituitary *gonadotrophins. It may be used to test the ability of the pituitary to produce gonadotrophins. *Gonadorelin analogues are used to treat endometriosis, fibroids, some types of infertility, and prostate cancer.... gonadotrophin-releasing hormone
see human placental lactogen.... human chorionic somatomammotrophin
see HIV.... human immunodeficiency virus
see HLA system.... human leucocyte antigen system
commercially available preparations of *follicle-stimulating hormone and *luteinizing hormone. They are used mainly to treat infertility in women with gonadotrophin deficiency due to hypopituitarism and to stimulate superovulation in women undergoing in vitro fertilization.... human menopausal gonadotrophins
(human chorionic somatomammotrophin) a protein hormone of 190 amino acids produced by the placenta during most but not all pregnancies. Despite its name it does not appear to have a role in lactation and its exact function remains obscure. It does, however, seem to contribute to the development of diabetes in some pregnancies.... human placental lactogen
a legal framework adopted by the United Nations following World War II that sought to define and promote fundamental entitlements, conditions, and freedoms to be afforded to all human beings. In the UK the Human Rights Act 1998 enacts the provisions of the 1950 European Convention on Human Rights, which sets out, via fourteen articles, an individual’s rights, entitlements, and freedoms.... human rights
Acts of the UK parliament in 1990 and 2008, establishing and amending principles for the legal supervision, by the Human Fertilisation and Embryology Authority, of the creation, use, and storage of human embryos outside the body and of their use in treatment and research. The 2008 amendments included a ban on sex selection for social reasons, recognition of same-sex couples as potential legal parents, and regulations related to developing areas of research using embryos. The 1990 Act had also reduced the legal time limit for most abortions from 28 weeks gestation (as in the 1967 Abortion Act) to 24 weeks. Interpretation and regulation of principles and practice in this rapidly developing area of research and practice continue and are often controversial.... human fertilisation and embryology acts
a massive international research project to isolate all the genes in human DNA and determine the sequence of genes on human chromosomes. The project began in 1988 and the full draft sequence was published in 2001; the high-quality sequence was completed in 2003. The human genome comprises some 3 × 109 nucleotide base pairs (see DNA) forming 22,000–25,000 genes, distributed among 23 pairs of chromosomes. Knowledge of the entire human genome has already resulted in the identification of the genes associated with many hereditary disorders and revealed the existence of a genetic basis or component for many other diseases not previously known to have one. Theoretically, this would enable the development of targeted drugs and the large-scale genetic screening of populations. See pharmacogenomics; targeted agent.... human genome project
the UK government agency, established by the Human Tissue Act 2004, that regulates the removal, use, and storage of human organs and tissue from both the living and the deceased for certain purposes as defined by the statute. These purposes include clinical research, clinical audit, and medical education. Anyone handling such material for those purposes should have a licence issued by the authority. Membership of the authority comprises clinical, scientific, academic, and lay representatives.... human tissue authority
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