leuco-comb. form

1863 H. B. Jones & A. W. Hoffman Fownes's Man. Elem. Chem. (ed. 9) 673 The action of sulphide of ammonium upon rosaniline gives rise to a base, leucaniline..which contains two additional equivalents of hydrogen.

1935 G. M. & R. Robinson in Jrnl. Chem. Soc. 745 Probably class (b) [of leuco-anthocyanins] consists of relatively simple glycosides or diglycosides, whereas members of class (c) are sugar-free and should be regarded as leuco-anthocyanidins.

1962 J. Clark-Lewis in T. A. Geissman Chem. Flavonoid Compounds viii. 218 Choice between the terms leucoanthocyanin and leucoanthocyanidin seems so far to have rested on the preference of individual authors, but there are sound reasons for using leucoanthocyanidin for the sugar-free molecules, and as the general term, and for reserving the term leucoanthocyanin for leucoanthocyanidin glycosides. The terminations thus have the same significance as in anthocyanin and anthocyanidin. All the compounds of this class and known constitution so far discovered in nature are leucoanthocyanidins, i.e. do not contain sugar residues.

1967 J. B. Harborne Compar. Biochem. Flavonoids ix. 302 Leuco~anthocyanidins (or condensed tannins) can be classified into three groups: (1) low molecular weight substances, which are probably dimers formed by linkage of a flavan-3,4-diol with a catechin.., (2) soluble oligomers, containing 4 to 8 flavan units, and (3) insoluble polymers (flavolans) of 10 or more units.

1967 New Scientist 4 May 270/3 The culprits that cause colour change in African mahogany are katechin and leucoanthocyanidin.

1920 O. Rosenheim in Biochem. Jrnl. XIV. 185 In the young leaf, however, the pseudo~base does not occur in the free state, but in combination with either a carbohydrate or possibly another complex. For this combination the general name leuco-anthocyanin is proposed.

1960 L. H. Meyer Food Chem. vii. 251 Catechins and leucoanthocyanins are present in the tissues of those woody plants studied such as apples, peaches, grapes, almonds, and some pears, while they are absent in herbaceous plants.

1962 T. Swain in T. A. Geissman Chem. Flavonoid Compounds xvi. 536 It has been presumed by many workers that the term leucoanthocyanin, like the term catechin, refers to the monomeric C₁₅ molecule.

1971 Ann. de Technol. Agricole XX. 32 Different methods for the dosage of leucoanthocyanins of white wines have been compared.

1901 Brit. Med. Jrnl. 29 June 1606 A partial exhaustion of the leucoblastic function of the bone marrow.

1742 T. Gray Let. 27 May in Corr. (1971) I. 209 Mine..is a white Melancholy, or rather Leucocholy for the most part; which though it seldom laughs or dances, nor ever amounts to what one calls Joy or Pleasure, yet is a good easy sort of a state.

1894 Jrnl. Royal Microsc. Soc. 732 The virulent cocci [of Staphylococcus]..secrete a special substance. This, which causes the death of the leucocytes, is termed ‘substance leucocide’ or leucocidine.

1909 J. G. Adami Princ. Pathol. I. iii. viii. 489 The leukotoxins are also known as leukocidins.

1970 E. J. Ambrose & D. M. Easty Cell Biol. xiv. 470 Some bacteria not only resist phagocytosis but produce substances, known as leucocidins, which kill phagocytes.

1909 A. Harker Nat. Hist. Igneous Rocks v. 112 The former [sc. camptonite, is] a melanocratic type..and the latter [sc. mænaite] leucocratic.

1954 H. Williams et al. Petrogr. ii. 33 In Johannsen's classification four rock classes are distinguished according to the volume-content of dark minerals, the limits being placed at 5, 50, and 95 percent. Shand also distinguishes four classes, but with different limits, as follows: leucocratic rocks, with less than 30 percent mafic minerals; mesocratic rocks, with 30–60 percent; melanocratic rocks, with 60–90 percent; and hypermelanic rocks, with more than 90 percent mafic minerals.

1965 G. J. Williams Econ. Geol. N.Z. xiv. 216/1 The Separation Point granite..is a massive white leucocratic soda-granite.

1829 Nat. Philos. (Libr. Useful Knowl.) I. Defract. & Polaris. Light ix. 34 In other specimens of apophyllite, which Mr. Herschel calls leucocyclite, from the rings being white and black.

1924 A. C. Haddon Races of Man (ed. 2) 13 Occasionally in leucoderms, sometimes in Negroes, and as a rule in Mongoloid peoples, a fold of skin..covers the inner angle of the eye.

1924 A. C. Haddon Races of Man (ed. 2) 84 The western steppe lands seem to have been the original home of fair (leucoderm) dolichocephals.

1935 J. S. Huxley & A. C. Haddon We Europeans iv. 115 A broad and convenient classification of skin-colour is as follows: (1) Leucoderms, or white-skinned (Caucasian) peoples; (2) Xanthoderms, or yellow-skinned peoples; (3) Melanoderms, or black-skinned peoples.

1884 F. M. Müller in 19th Cent. June 1017 A semi-human progenitor, suffering, it may be, from leprosy or leucoderma.

1888 New Sydenham Soc. Lexicon Leucodermia, see Leukoderma.

1908 Practitioner Aug. 349 They [sc. freckles] are an example of excess of pigment in the skin, a condition known as hyperchromasia, in contradistinction to achromasia, or leucodermia, in which there is a deficiency of pigment in the skin.

1926 H. H. Wilder Pedigree of Human Race vi. 348 Members of the Leucodermic race in Europe or America.

1898 T. C. Allbutt et al. Syst. Med. V. 418 Any number of leucocytes below the arbitrary limit of 6000 [per cubic millimetre of blood] will constitute a hypoleucocytosis, or leucopenia as the condition is also named.

1961 R. D. Baker Essent. Pathol. ii. 18 In some inflammations the total white blood cell count is decreased (leukopenia).

1964 W. G. Smith Allergy & Tissue Metabolism ii. 16 Marked reductions in the number of leucocytes (leukopenia) and platelets (thrombocytopenia) circulating in the blood were described.

1898 T. C. Allbutt et al. Syst. Med. V. 420 He was able to distinguish..a leucopenic phase, or hypoleucytosis, during which the number of hæmic leucocytes falls [etc.].

1924 L. Hogben Pigment. Effector Syst. ii. 24 In the skin of the Chameleon there are present, immediately below the epidermis, cells charged with yellow pigment variously described as guanophores (Schmidt), leukophores or ochrophores (Keller), iridocytes (Pouchet), or interference cells (Brucke).

1963 M. Fingerman Control of Chromatophores i. 4 When the guanine consists of fine granules that can migrate the term leucophore is usually employed.

1932 E. S. Simpson in Jrnl. Royal Soc. W. Austral. XVIII. 71 No previously described mineral approaches this in composition except minervite, a potassium aluminium phosphate, from which it differs in possessing a much greater basicity... It appears therefore to be a new species for which the name Leucophosphite is suggested.

1963 Prof. Papers U.S. Geol. Surv. No. 475 –C. 103/2 Leucophosphite and gypsum represent in large part only a recombination of the elements already present in the phosphatized wood when uplift of the enclosing Moreno Formation exposed it to weathering.

1972 Amer. Mineralogist 57 397 Leucophosphite, K₂[Fe³⁺₄(OH)₂(H₂O)₂(PO₄)₄].2H₂O, possesses an atomic arrangement based on a discrete octahedral tetramer.

1865 H. Watts Dict. Chem. III. 584 Leucophyll.

a1883 C. H. Fagge Princ. & Pract. Med. (1886) I. 124 A similar affection of the tongue often follows leucoplacia, or white syphilitic patches, at the end of several years.

1920 W. E. Masters Essent. Trop. Med. vi. 477 Leucoplakia may also affect the penis, vulva and vagina.

1962 Lancet 1 Dec. 1170/2 Leucoplakia (or lichen sclerosus) diagnosed by the clinician on naked-eye appearances shows variable and non-specific histological features.

1962 Lancet 8 Dec. 1228/2 Here operating is undesirable, except in those few patients in whom leukoplakia develops as well.

1973 Daily Colonist (Victoria, Brit. Columbia) 7 Sept. 2/1 Leukoplakia is a thickening of the membrane of a mucous surface, commonly on the lip or in the mouth.

1886 Jrnl. Royal Microsc. Soc. 6 640 In the lower plants..the formation of leucoplasts is a subsequent process, a transformation of the coloured into a colourless chromatophore.

1887 W. Hillhouse tr. E. Strasburger Handbk. Pract. Bot. iv. 44 We can..distinguish the chlorophyll-bodies, colour-bodies, and colourless starch-builders as Chloroplasts, Chromoplasts, and Leucoplasts respectively.

1902 H. Wager in Encycl. Brit. XXVII. 333/1 As the cell grows they [sc. the chromatophores] may become converted into leucoplasts (starch-formers), chloroplasts (chlorophyll-bodies), or chromoplasts (colour-bodies).

1964 Oceanogr. & Marine Biol. 2 199 All species [of the genus Caulerpa of green algae] possess amyliferous leucoplasts as well as the ordinary green plastids.

1885 G. L. Goodale in A. Gray & G. L. Goodale Bot. Text-bk. (ed. 6) II. i. i. 43 Leucoplastids..are found in parts which are normally devoid of chlorophyll, such as tubers, rhizomes, etc.

1913 W. A. N. Dorland Illustr. Med. Dict. (ed. 7) 512/2 Leukopoiesis, production of leukocytes.

1942 M. M. Wintrobe Clin. Hematol. i. 26 Erythropoiesis in the spleen is at first more pronounced than leukopoiesis but it is short-lived.

1973 Woodliff & Herrmann Conc. Haematol. viii. 113 Disorders of leucopoiesis are usually reflected by changes in the peripheral blood.

1913 W. A. N. Dorland Illustr. Med. Dict. (ed. 7) 512/2 Leukopoietic, forming or producing leukocytes.

1927 A. Piney Recent Adv. in Hæmatol. iii. 35 Hyperplasias of a character similar to those occurring in the leucopoietic tissue may affect the erythropoietic one.

1973 Woodliff & Herrmann Conc. Haematol. viii. 113 A progressive malignant proliferation of the leucopoietic tissues.

1927 Chem. Abstr. 21 224 (heading) Leucopterin, the white wing pigment of cabbage butterflies (Pieris brassicae and P. napi).

1954 Sci. News 34 91 The purines and pterines contribute a major source of colour to the wings of butterflies... These compounds are only present in small amounts representing in the case of white leucopterin of Pierid butterflies about 0·18 milligramme per specimen.

1883 Nature 18 Jan. 277/1 Prof. Helmholtz's new instrument, called the leukoscope.

1871 tr. H. Schellen Spectrum Anal. lvi. 272 For this envelope the name ‘leucosphere’ has been proposed.

1937 V. Menkin in Proc. Soc. Exper. Biol. & Med. 36 167 For the sake of convenience the name leukotaxine is tentatively proposed for this active crystalline nitrogenous substance which is evidently released by injured tissue and is readily recovered in inflammatory exudates.

1947 New Biol. 2 135 The most reasonable hypothesis is..that leucotaxine is released from the killed and damaged cells of the injured skin we are considering, and is mainly responsible for the escape of fluid from nearby undamaged capillaries.

1957 Amer. Jrnl. Physiol. 189 99 (caption) A preliminary intravenous injection of 25 mg of cortisone acetate was performed in the tested rabbit to inactivate the masking effect of any leukotaxine possibly present in the acid exudate to be injected.

1964 W. G. Smith Allergy & Tissue Metabolism iii. 39 This material, which Menkin called leucotaxin, can upon injection into the skin induce increased capillary permeability and chemotactic attraction of polymorphs to the injection site.

1908 Practitioner Mar. 392 Roentgen-rays appear to lead to the production of veritable ‘leucotoxins’. Normal leucocytes, exposed in vitro and in vivo to the action of such leucotoxins present in the serum of animals, which have been exposed to Roentgen-rays, undergo a specific disintegration.

1931 Biol. Abstr. 5 488/2 The virulent streptococci do not possess in the same degree the power of leukotoxin production.

1956 Proc. Soc. Exper. Biol. & Med. 93 493/2 A leucotoxin develops in the blood of the rabbit in hemorrhagic shock, and..this leucotoxin severely impairs the antibacterial potential of the animal.

1908 Practitioner Sept. 354 I believe that if sufficient examinations were made in syphilitic patients..leucoplakial patches would be found in the mucous membrane from time to time.

1923 Surg., Gynecol. & Obstetr. 36 189/1 The leukoplakial conditions of the urinary tract have received relatively little attention.

1907 Arch. Middlesex Hosp. IX. (6th Rep. Cancer Res. Lab.) 65 Those leucoplakic conditions of vulva, tongue, and lips which..often precede the development of squamous cell carcinoma.

1917 J. Bland-Sutton Tumours, Innocent & Malignant (ed. 6) xxx. 331 In some patients an ulcer appears in a leucoplakic patch.

1962 Lancet 1 Dec. 1170/2 If all vulvas described as leucoplakic on clinical grounds are subjected to biopsy, approximately 5% are found to be cancerous at the outset.

1962 Lancet 8 Dec. 1228/2 Changes in vulval skin..are very common... Among other features, they are often white, but this does not mean that they are precancerous or leukoplakic.

1886 E. Knecht tr. R. Benedikt Chem. Coal-tar Colours 79 These compounds, called ‘leuco-bases’, are colourless and yield colourless salts with acids. By oxidation they are transformed..into the colour-bases, which differ from the ‘leuco-bases’ by containing one atom of oxygen.

1947 L. S. Pratt Chem. & Physics Org. Pigments viii. 140 The dyestuff is prepared by condensing o-chlorobenzaldehyde with dimethylaniline and then oxidizing the leuco base to the color base.

1958 J. R. Baker Princ. Biol. Microtechnique xvii. 309 Schiff's reagent..is often regarded as a leucobase, but this is an error; for a leucobase becomes coloured on oxidation and could not possibly serve in Feulgen's reaction.

1971 E. Gurr Synthetic Dyes 108 The leuco bases of triphenylmethane dyes (e.g. crystal violet and malachite green) are extremely light sensitive.

1956 Nature 14 Jan. 92/2 Leuco-basic fuchsin is specific for deoxyribonucleic acid.

1970 Watsonia 8 23 Root tips..were..stained in leucobasic fuchsin.

1888 Jrnl. Chem. Soc. 54 493 The anthraquinone-dyes yield leuco~compounds on reduction.

1906 Notices Proc. Royal Inst. Great Brit. 17 107 What we are pleased to call leucocompounds, are in the majority of cases by no means colourless. Indigo-white itself is not white but yellow in its alkaline solution which we call a vat. Other vat-dyes have leucocompounds which are even more strongly coloured.

1961 S. R. Cockett & K. A. Hilton Dyeing of Cellulosic Fibres viii. 280 All methods used in practice to apply vat dyes to cellulosic fibres involve, at some stage, the conversion of the insoluble vat dye to the soluble sodium salt of the so-called leuco compound of the dye.

1931 Trans. Faraday Soc. 27 571 The pure alcoholic leuco cyanide solution is very suitable for a laboratory method [of measuring ultra-violet light].

1965 J. Kosar Light-sensitive Syst. viii. 370 Aside from the photographic applications, light-sensitive leucocyanides are useful for detecting, measuring, and recording short wave ultraviolet light.

1954 Textile Terms & Definitions (Textile Inst.) 24 Leuco dye, a reduced form of dye from which the original dye may be regenerated by an oxidation process.

1973 J. F. Willems in R. J. Cox Proc. Symposium Photogr. Processing Univ. Sussex 95 These leuco dyes are strong reducing agents, which in the adsorbed state on the silver halide grain start the development.

1959 Nature 15 Aug. 545/1 The production of a coloured dye by transformation of the leuco form.

1945 Chem. Abstr. 39 Index 6288/1 Leuco~fuchsin.

1965 E. Gurr Rational Use of Dyes in Biol. 94 Solutions of reduced dyes, such as Schiff's reagent (leuco fuchsin), leuco acid fuchsin and leuco patent blue in distilled water, are oxidized on heating and consequently restored in colour.

1967 Jrnl. Med. Lab. Technol. 24 48 (heading) Nitric acid leucofuchsin technique for myelinated nerves.