| J | Symbol for joule; Joule's equivalent; electric current density, flux. (05 Mar 2000) |
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| J chain | <molecular biology> A polypeptide chain (15 kD), found in IgA and in IgM joining heavy chains (H chains) to each other to form dimers of IgA and pentamers of IgM. Disulphide bonds are formed between the J chain and H chains near the Fc ends of the heavy chains. Despite the similar name, it is not identical with the J region or coded for by the J gene. Synonym: J piece. (10 Jan 1998) |
| J gene | <molecular biology> Gene or genes coding for the Joining segment of polypeptide chain which links the V (variable regions) to the C (constant) regions of both Light and Heavy chains of immunoglobulins. During lymphoid development the DNA is rearranged so that the V genes are linked to the J region sequences. (18 Nov 1997) |
| J point | The point marking the end of the QRS complex and the beginning of the S or T wave in the electrocardiogram. Synonym: ST junction. (05 Mar 2000) |
| J region | <molecular biology> The polypeptide chains coded for by J genes. (18 Nov 1997) |
| j-g complex | A complex consisting of the juxtaglomerular cells, which are modified smooth muscle cells in the wall of the afferent glomerular arteriole and sometimes also the efferent arteriole; extraglomerular mesangium lacis cells, which are located in the angle between the afferent and efferent glomerular arterioles; the macula densa of the distal convoluted tubule; and granular epithelial peripolar cells located at the angle of reflection of the parietal to the visceral capsule of the renal corpuscle; believed to provide some feedback control of extracellular fluid volume and glomerular filtration rate. Synonym: j-g complex, juxtaglomerular apparatus. (05 Mar 2000) |
| J-sella deformity | Pear-shaped or J-shaped deformity of sella turcica caused by increased pressure on growing sphenoid bone; noted in the mucopolysaccharide storage diseases. (05 Mar 2000) |
| j-shaped sella | <radiology> Cretinism (hypothyroidism), optic glioma, neurofibromatosis, Hurler syndrome (MPS I), mild arrested hydrocephalus, normal variant (12 Dec 1998) |
| jaagsiekte | Synonym: pulmonary adenomatosis of sheep. Origin: Afrikaans, drive sickness (05 Mar 2000) |
| jaal goat | <zoology> A species of wild goat (Capra Nubiana) found in the mountains of Abyssinia, Upper Egypt, and Arabia. Synonym: beden, and jaela. Source: Websters Dictionary (01 Mar 1998) |
| jabiru | <ornithology> One of several large wading birds of the genera Mycteria and Xenorhynchus, allied to the storks in form and habits. The American jabiru (Mycteria Americana) is white, with the head and neck black and nearly bare of feathers. The East Indian and Australian (Xenorhynchus Australis) has the neck, head, and back covered with glossy, dark green feathers, changing on the head to purple. The African jabiru (Mycteria, or Ephippiorhynchus, Senegalensis) has the neck, head, wing coverts, and tail, black, and is Synonym: saddle-billed stork. Origin: Braz. Jabiro, jaburo. Source: Websters Dictionary (01 Mar 1998) |
| jaborandi | <botany> The native name of a South American rutaceous shrub (Pilocarpus pennatifolius). The leaves are used in medicine as an diaphoretic and sialogogue. Source: Websters Dictionary (01 Mar 1998) |
| jaborine | <chemistry> An alkaloid found in jaborandi leaves, from which it is extracted as a white amorphous substance. In its action it resembles atropine. Origin: From Jaborandi. Source: Websters Dictionary (01 Mar 1998) |
| Jaboulay pyloroplasty | A side-to-side gastroduodenostomy, useful when the pylorus and proximal duodenum are extensively scarred or indurated by peptic ulcer disease. (05 Mar 2000) |
| Jaboulay's amputation | Amputation of a lower limb through the sacroiliac joint. (12 Dec 1998) |