| periocular | Around the eye. Synonym: periocular, periophthalmic. Origin: circum-+ L. Oculus, eye (05 Mar 2000) |
|---|---|
| period | Drosophila gene regulating circadian rhythm. See: timeless. (18 Nov 1997) |
| periodate | <chemistry> A salt of periodic acid. Source: Websters Dictionary (01 Mar 1998) |
| periodic | Recurring at regular intervals of time. Origin: Gr. Periodikos (18 Nov 1997) |
| periodic acid | <chemical> Periodic acid (h5io6). A strong oxidizing agent. Chemical name: Periodic acid (H5IO6) (12 Dec 1998) |
| periodic acid Schiff reaction | <technique> A histochemical technique based on periodic acid oxidation of a substance containing the 1,2-glycol grouping. It is used for staining carbohydrates as the resulting dialdehyde reacts with Schiff reagent to form a coloured product. The adjacent hydroxyl groups are oxidized to form aldehydes by periodic acid (HIO4) and these aldehyde groups react with Schiff's reagent (basic fuchsin decolourised by sulphurous acid) to give a purple colour. Acronym: PAS (18 Nov 1997) |
| periodic acid Schiff stain | <technique> A histochemical technique based on periodic acid oxidation of a substance containing the 1,2-glycol grouping. It is used for staining carbohydrates as the resulting dialdehyde reacts with Schiff reagent to form a coloured product. Substances that can be demonstrated include carbohydrates, mucins, cartilage matrix, collagen, reticulum, basement membranes, fibrin, thyroid colloid, amyloid, glomerular hyaline deposits, and a number of other secretions or tissue constituents. Also used in for staining gels on which glycoproteins have been run. See: periodic acid Schiff reaction Synonym: PAS stain. (22 Sep 2002) |
| periodic arthralgia | A condition in which pain and swelling of one or more joints, most commonly the knee, occurs at regular intervals; there is sometimes abdominal pain, purpura, or oedema. Synonym: intermittent arthralgia. (05 Mar 2000) |
| periodic biopolymer | A biopolymer in which there are identical, repeating subunits. (05 Mar 2000) |
| periodic catatonia | Regularly reappearing phases of catatonic excitement. (05 Mar 2000) |
| periodic disease | A condition characterised by regularly recurring and intermittent episodes of fever, oedema, arthralgia, and gastric pain and vomiting, continuing for years without further development in otherwise healthy individuals. It is also called familial mediterranean fever. It does not refer to conditions in which episodes recur at regular intervals. (12 Dec 1998) |
| periodic fever | An obsolete term introduced to describe the intermittent febrile episodes seen in disease later recognised and named familial Mediterranean fever. (05 Mar 2000) |
| periodic filariasis | A form of filariasis in which microfilariae appear in the peripheral blood at regular 24-hr intervals; usually refers to the nocturnal periodicity of bancroftian filariasis. (05 Mar 2000) |
| periodic law | The properties of elements are periodical functions of their atomic weights; i.e., if the elements are arranged in the order of their atomic weights, every element in the series will be related in respect to its properties to the eighth in order before or after it. Synonym: periodic law. (05 Mar 2000) |
| periodic migrainous neuralgia | Recurrent facial pain and headache, more common in men than in women. Synonym: Harris' migraine. (05 Mar 2000) |