Sex Determination: From 1 Different Sources
The factors that determine biological sex. The underlying determinants are the sex chromosomes which cause the differential development of the gonads in the embryo. In males, the testes then produce hormones that cause the male reproductive organs to
form. In the absence of these hormones, a female reproductive tract develops. At puberty, another surge of hormones produces secondary sexual characteristics.
Chromosomal abnormalities or hormonal defects can lead to ambiguous sex (see genitalia, ambiguous), although true hermaphroditism is rare.
Analysis means a separation into component parts by determination of the chemical constituents of a substance. The process of analysis is carried out by various means, for example: chromatographic analysis by means of the adsorption column; colorimetric analysis by means of various colour tests; densimetric analysis by estimation of the speci?c gravity; gasometric analysis by estimation of the di?erent gases given o? in some process; polariscope analysis by means of the polariscope; and volumetric analysis by measuring volumes of liquids. Analysis is also sometimes used as an abbreviation for PSYCHOANALYSIS.... analysis
This is a colourless, odourless, tasteless, nonirritating gas formed on incomplete combustion of organic fuels. Exposure to CO is frequently due to defective gas, oil or solid-fuel heating appliances. CO is a component of car exhaust fumes and deliberate exposure to these is a common method of suicide. Victims of ?res often suffer from CO poisoning. CO combines reversibly with oxygen-carrying sites of HAEMOGLOBIN (Hb) molecules with an a?nity 200 to 300 times greater than oxygen itself. The carboxyhaemoglobin (COHb) formed becomes unavailable for oxygen transportation. In addition the partial saturation of the Hb molecule results in tighter oxygen binding, impairing delivery to the tissues. CO also binds to MYOGLOBIN and respiratory cytochrome enzymes. Exposure to CO at levels of 500 parts per million (ppm) would be expected to cause mild symptoms only and exposure to levels of 4,000 ppm would be rapidly fatal.
Each year around 50 people in the United Kingdom are reported as dying from carbon monoxide poisoning, and experts have suggested that as many as 25,000 people a year are exposed to its effects within the home, but most cases are unrecognised, unreported and untreated, even though victims may suffer from long-term effects. This is regrettable, given that Napoleon’s surgeon, Larrey, recognised in the 18th century that soldiers were being poisoned by carbon monoxide when billeted in huts heated by woodburning stoves. In the USA it is estimated that 40,000 people a year attend emergency departments suffering from carbon monoxide poisoning. So prevention is clearly an important element in dealing with what is sometimes termed the ‘silent killer’. Safer designs of houses and heating systems, as well as wider public education on the dangers of carbon monoxide and its sources, are important.
Clinical effects of acute exposure resemble those of atmospheric HYPOXIA. Tissues and organs with high oxygen consumption are affected to a great extent. Common effects include headaches, weakness, fatigue, ?ushing, nausea, vomiting, irritability, dizziness, drowsiness, disorientation, incoordination, visual disturbances, TACHYCARDIA and HYPERVENTILATION. In severe cases drowsiness may progress rapidly to COMA. There may also be metabolic ACIDOSIS, HYPOKALAEMIA, CONVULSIONS, HYPOTENSION, respiratory depression, ECG changes and cardiovascular collapse. Cerebral OEDEMA is common and will lead to severe brain damage and focal neurological signs. Signi?cant abnormalities on physical examination include impaired short-term memory, abnormal Rhomberg’s test (standing unsupported with eyes closed) and unsteadiness of gait including heel-toe walking. Any one of these signs would classify the episode as severe. Victims’ skin may be coloured pink, though this is very rarely seen even in severe incidents. The venous blood may look ‘arterial’. Patients recovering from acute CO poisoning may suffer neurological sequelae including TREMOR, personality changes, memory impairment, visual loss, inability to concentrate and PARKINSONISM. Chronic low-level exposures may result in nausea, fatigue, headache, confusion, VOMITING, DIARRHOEA, abdominal pain and general malaise. They are often misdiagnosed as in?uenza or food poisoning.
First-aid treatment is to remove the victim from the source of exposure, ensure an e?ective airway and give 100-per-cent oxygen by tight-?tting mask. In hospital, management is largely suppportive, with oxygen administration. A blood sample for COHb level determination should be taken as soon as practicable and, if possible, before oxygen is given. Ideally, oxygen therapy should continue until the COHb level falls below 5 per cent. Patients with any history of unconsciousness, a COHb level greater than 20 per cent on arrival, any neurological signs, any cardiac arrhythmias or anyone who is pregnant should be referred for an expert opinion about possible treatment with hyperbaric oxygen, though this remains a controversial therapy. Hyperbaric oxygen therapy shortens the half-life of COHb, increases plasma oxygen transport and reverses the clinical effects resulting from acute exposures. Carbon monoxide is also an environmental poison and a component of cigarette smoke. Normal body COHb levels due to ENDOGENOUS CO production are 0.4 to
0.7 per cent. Non-smokers in urban areas may have level of 1–2 per cent as a result of environmental exposure. Smokers may have a COHb level of 5 to 6 per cent.... carbon monoxide (co)
A method for the determination of health insurance premiums that spreads the risk among members of a large community and establishes premiums based on the utilization experience of the whole community. For a set of benefits, the same rate applies to everyone regardless of age, gender, occupation or any other indicator of health risk.... community rating
A determination of the least costly among alternative interventions that are assumed to produce equivalent outcomes.... cost minimization analysis
A determination of the economic impact of a disease or health condition, including treatment costs.... cost-of-illness analysis
The process of determining health status and the factors responsible for producing it. It may be applied to an individual, family, group or community. The term is applied both to the process of determination and to its findings. See also “principal diagnosis”.... diagnosis
The basic evaluative principles which (should) guide “good” care. Principles typically refer to respect for, and the dignity of, human beings. Basic dimensions are “autonomy” (respect for self determination), “well-being” (respect for happiness, health and mental integrity) and “social justice” (justifiable distribution of scarce goods and services). More specifically, ethics of care refer to ethical standards developed for the care professions which are designed to implement ethical principles in the practice of care provision.... ethics (of care)
Living at home without the need for continuous help and with a degree of self determination or control over one’s activities.... independent living
The determination of eligibility for a publicly financed programme on the basis of an applicant’s income and assets (means).... means test
(French) A woman with great strength and determination Melicent, Mellicent, Mellie, Mellisent, Melly, Milicent, Milisent, Millisent, Milzie, Milicente... millicent
1 The quality of being sharply defined or stated. One measure of precision is the number of distinguishable alternatives from which a measurement was selected, sometimes indicated by the number of significant digits in the measurement. Another measure of precision is the standard error of measurement, the standard deviation of a series of replicate determinations of the same quantity. Precision does not imply accuracy. 2 In statistics, precision is defined as the inverse of the variance of a measurement or estimate.... precision
Determination of the identity of a substance or of the individual chemical constituents of a mixture. Analysis may be qualitative, as in determining whether a particular substance is present, or it may be quantitative, that is, measuring the amount or concentration of one or more constituents. (See also assay.)... analysis, chemical
A group of abnormalities in which the affected person has ambiguous genitalia (abnormal external sex organs) or external genitalia that have the opposite appearance to the chromosomal sex of the individual (see sex determination).... intersex
A pair of chromosomes that determines an individual’s sex. All human cells (except egg or sperm cells) contain a pair of sex chromosomes, together with 22 other pairs of chromosomes called autosomes. In women, there are 2 similar sex chromosomes called X chromosomes. Men have 1 X and 1 Y chromosome. The genes on the Y chromosome are concerned solely with sex determination; their presence ensures a male, their absence a female. The X chromosome carries genes vital to general development and functioning.... sex chromosomes
n. literally ‘self-rule’, the capacity for reasoned self-determination in thought and action. Respect for the autonomy of all persons with capacity, particularly patients, is one of the *four principles of medical ethics. In practice, a patient’s capacity to exercise autonomy may be constrained by various circumstances, but in law it is formally safeguarded by the need for valid *consent to treatment or research. Autonomy is not unlimited in its scope, e.g. as a general principle, patients can request but not demand treatment. Professional autonomy involves *reflective practice and attempting to follow one’s own principles consistently and confidently. —autonomous adj.... autonomy
(differential blood count) a determination of the proportions of the different kinds of white cells (leucocytes) present in a sample of blood. Usually 100 white cells are counted and classified under the microscope or by electronic apparatus, so that the results can readily be expressed as percentages of the total number of leucocytes and the absolute numbers per litre of blood. The information often aids diagnosis of disease.... differential leucocyte count
n. the appearance of a fernlike pattern in a dried specimen of cervical mucus, an indication of the presence of oestrogen, usually seen at the midpoint of the menstrual cycle. It can be helpful in the determination of ovulation. The same phenomenon occurs with premature rupture of the membranes (see fibronectin).... ferning
a standardized assessment procedure for the determination of intellectual ability. The score produced is usually expressed as an *intelligence quotient. Most tests present a series of different kinds of problems to be solved. The best known are the Wechsler Adult Intelligence Scale (WAIS), the Wechsler Intelligence Scale for Children (WISC), and the Stanford Binet Intelligence Scale. Scores on intelligence tests are used for such purposes as the diagnosis of *learning disability and the assessment of intellectual deterioration.... intelligence test
major histocompatibility complex: a series of genes located on chromosome no. 6 that code for antigens, including the *HLA antigens, that are important in the determination of histocompatibility.... mhc
n. the study of the phenomena of death, involving determination of the moment of death and the different changes that occur in the tissues of the body after death.... necrology
n. failure by a health-care professional to exercise a reasonable standard of care, as defined in the UK by the *Bolam and Bolitho tests, which ask whether the care provided fell short of that of a reasonable body of professional opinion and whether actions or omissions withstand logical analysis (the determination of which falls to the court). In order to establish negligence a claimant must show that a doctor had a *duty of care, that he or she breached this duty by falling below the expected standard of care, and that foreseeable harm was caused as a result of the professional’s conduct. The standard of proof in negligence actions is that of the civil law (i.e. on the balance of probabilities). Payment of *compensation to the claimant upon proving negligence is required by the UK civil law. Rarely, doctors may be charged with the criminal offence of manslaughter by gross negligence, which must be proved according to the standards of the criminal law (beyond reasonable doubt). If convicted, the sentence for gross negligence cases is likely to be custodial.... negligence
(antenatal diagnosis) diagnostic procedures carried out on pregnant women in order to detect the presence of genetic or other abnormalities in the developing fetus. Ultrasound scanning (see ultrasonography) remains the cornerstone of prenatal diagnosis. Other procedures include chromosome and enzyme analysis of fetal cells obtained by *amniocentesis or, at an earlier stage of pregnancy, by *chorionic villus sampling (CVS). Noninvasive prenatal diagnosis involves a blood test to analyse cell-free fetal DNA in maternal blood. It can be performed during the first trimester and is used for fetal rhesus (Rh) determination in Rh-negative mothers, fetal sex determination in pregnancies at risk of sex-linked disorders, and for some single-sex gene disorders (e.g. achondroplasia). Compare prenatal screening.... prenatal diagnosis
a chromosome that is involved in the determination of the sex of the individual. Women have two *X chromosomes; men have one X chromosome and one *Y chromosome. Compare autosome.... sex chromosome
determination of the *HLA profiles of tissues to assess their compatibility. It is the most important predictor of success or failure of a transplant operation.... tissue typing
n. 1. the change in direction of light rays when they pass obliquely from one transparent medium to another, of a different density. Refraction occurs as light enters the eye, when it passes from air to the media of the eye, i.e. cornea, aqueous humour, lens, and vitreous humour, to come to a focus on the retina. Errors of refraction, in which light rays do not come to a focus on the retina due to defects in the refracting media or shape of the eyeball, include astigmatism and long- and short-sightedness. 2. determination of the power of refraction of the eye. This gives the degree to which the eye differs from normal, which will determine whether or not the patient needs glasses and, if so, how strong they should be.... refraction
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