PURPURA

This article appears in Volume V22, Page 665 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: PRE-PYR

PURPURA , in

pathology

PATHOLOGY (from Gr. raBos, suffering)

, a general term for the symptom of purple-coloured spots upon the surface of the

body

BODY

, due to extravasations of blood in the skin, accompanied occasionally with haemorrhages from mucous membranes. The varieties of purpura may be conveniently divided as follows: (a) toxic, following the administration of certain drugs, notably

copaiba

COPAIBA, or COPAIVA (from Brazilian cupauba)

, quinine, ergot, belladonna and the iodides; also following snake-bite; (b) cachectic, seen in persons suffering from such diseases as tuberculosis, heart disease, cancer,

Bright

BRIGHT, JOHN (1811-188g)
BRIGHT, SIR CHARLES TILSTON

's disease,

jaundice

JAUNDICE (Fr. jaunisse, from jaune, yellow), or IUTERUS (from its resemblance to the colour of the golden oriole, of which Pliny relates that if a jaundiced person looks upon it he recovers but the bird dies)

, as well as from certain of the infectious fevers, extravasations of the kind above mentioned being not infrequently present; (c) neurotic; (d) arthritic, which includes the form known as " Purpura simplex," in which there may or may not be articular pain, and the complaint is usually ushered in by lassitude and feverishness, followed by the

appearance

APPEARANCE (from Lat. apparere, to appear)

on the surface of the

body

BODY

of the characteristic spots in the form of small red points scattered over the skin of the limbs and trunk. The spots are not raised above the surface, and they do not disappear on pressure. Their colour soon becomes deep purple or nearly black; but after a few days they undergo the changes which are observed in the case of an

ordinary

ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

bruise, passing to a green and yellow hue and finally disappearing. When of minute size they are termed "petechiae" or " stigmata," when somewhat larger " vibices," and when in patches of considerable size " ecchymoses." They may come out in fresh crops over a lengthened period.
Purpura rheumatica (Schonlein's disease) is a remarkable variety characterized by sore throat, fever and articular pains accompanied by purpuric spots and associated with urticaria and occasionally with definite nodular infiltrations. This is by many writers considered to be a

separate

SEPARATE

disease, but it is usually regarded as of rheumatic origin.
Purpura haemorrhagica (acute haemorrhagic purpura) is a more serious form, in which, in addition to the phenomena already mentioned as affecting the skin, there is a tendency to the occurrence of

haemorrhage

HAEMORRHAGE (Gr. atľa, blood, and prryvvvac, to burst)

from mucous surfaces, especially from the nose, but also from the mouth, lungs, stomach, bowels, kidneys, &c., sometimes in large and dangerous amount.

Great

GREAT

physical prostration is apt to attend this form of the disease, and a fatal result some-times follows the successive haemorrhages, or is suddenly precipitated by the occurrence of an extravasation of blood into the brain.
(see above) by the action of aqueous ammonia at 15o C. It also results instead of the expected 7-methyl-2-oxy-6-aminopurin, when 7-methyl-6-amino-2-chlorpurin is treated with dilute alkalis (E. Fischer, Ber., 1898, 31, p. 542), owing to ring splitting in the 1.6-position, followed by eliminating of halogen acid.
Thiopurins.W. Traube (Ann., 1904, 331, pp. 66 seq.) has obtained many compounds of the purin group by using thiourea, which is condensed with cyanacetic ester, &c., to form thiopyrimidines. These in turn yield thiopurins, which on oxidation with dilute nitric acid are converted into purin compounds, thus:

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