| Liebig, Baron Justus von | <person> German chemist, 1803-1873. See: Liebig's theory. (05 Mar 2000) |
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| lindau-von hippel syndrome | <syndrome> The cardinal features of what is more commonly called von hippel-lindau (vhl) syndrome are benign blood-vessel tumours that most typically affect the eye and the brain. The eye tumours are termed angiomata and are in the retina. The brain tumours are termed haemangioblastoma and are in the cerebellum. Vhl is complex. There can also be blood-vessel tumours (haemangiomata) in the spinal cord, adrenal glands, liver, and lungs. Pheochromocytoma (a benign tumour of adrenal-like tissue) occurs in some patients. The combination of high blood pressure (hypertension) with angioma may cause bleeding under the skull (subarachnoid haemorrhage). Kidney tumours (like hypernephromas) may be malignant and metastasize. An abnormal elevation of red blood cells (polycythemia) can be due to the haemangioblastoma of the cerebellum or the hypernephroma. Multiple cysts can occur in the pancreas and kidneys. Patients with kidney problems or pancreatic cysts do not have pheochromocytoma, and visa versa. Lab findings in vhl may include high calcium (hypercalcaemia) and low potassium (hypokalaemia) occurring with the pheochromocytoma. Vhl is inherited as an autosomal dominant trait. The gene on one of the non-sex chromosomes is dominant over the normal gene with which it is paired so that one vhl gene is sufficient to cause the vhl syndrome. If a person has vhl, the chance for each of their children to receive the vhl gene is one-half (50%). The vhl gene has been mapped to chromosome 3 (the 3rd volume in the book of life) in region 3p26-p25. The vhl gene has the characteristics of a tumour-suppressor gene. The person with vhl inherits one inactive copy of the vhl gene (a germline mutation) from one of their parents. But the normal gene with which it is paired is still enough to suppress the formation of a tumour. Then, in one cell in the vhl patient's body, another mutation (a somatic mutation) occurs, inactivating the other vhl gene. Thus, both copies of the vhl gene are inactivated and a tumour arises in the vhl patient. The syndrome is named for the german ophthalmologist eugen von hippel who described the charcteristic eye blood-vessel tumours in 1904 and the swedish pathologist arvid lindau who recognised the association between the eye tumours and the blood-vessel tumours of the cerebellum and other parts of the central nervous system in 1926-7. (12 Dec 1998) |
| Ludwig, Wilhelm Friedrich von | <person> German surgeon, 1790-1865. See: Ludwig's angina. (05 Mar 2000) |
| Aaron's sign | <clinical sign> In acute appendicitis, a referred pain or feeling of distress in the epigastrium or precordial region on continuous firm pressure over McBurney's point. (05 Mar 2000) |
| Abadie's sign of tabes dorsalis | Insensibility to pressure over the tendo achillis. (05 Mar 2000) |
| Abrahams' sign | <clinical sign> An obsolete sign: Rales and other adventitious sounds, changes in the respiratory murmurs, and increase in the whispered sound can be heard on auscultation over the acromial end of the clavicle some time before they become audible at the apex; heard primarily in pulmonary tuberculosis affecting the apical portion of the lung, a dull-flat note, i.e., one between the normal dullness at the right apex and absolute flatness, heard on percussion in that region, indicating progress from incipient to advanced tuberculosis. (05 Mar 2000) |
| accessory sign | <clinical sign> A finding frequently but not consistently present in a disease. Synonym: assident sign. (05 Mar 2000) |
| Allis' sign | <clinical sign> In fracture of the neck of the femur, the trochanter rides up, relaxing the fascia lata, so that the finger can be sunk deeply between the great trochanter and the iliac crest. (05 Mar 2000) |
| Amoss' sign | <clinical sign> In painful flexion of the spine, it is necessary to support a sitting position by extending the arms behind the torso with the weight placed on the hands. (05 Mar 2000) |
| Anghelescu's sign | <clinical sign> In vertebral tuberculosis, painful or impossible flexion of the spine when the patient attempts to rest weight on the heels and occiput. (05 Mar 2000) |
| antecedent sign | <clinical sign> A sign that appears during the prodrome of a disease. Synonym: antecedent sign. (05 Mar 2000) |
| assident sign | <clinical sign> A finding frequently but not consistently present in a disease. Synonym: assident sign. (05 Mar 2000) |
| Auenbrugger's sign | <clinical sign> An epigastric prominence seen in cases of marked pericardial effusion. (05 Mar 2000) |
| Aufrecht's sign | <clinical sign> An obsolete sign: diminished breath sounds in the trachea just above the jugular notch, in cases of stenosis. (05 Mar 2000) |
| B6 bronchus sign | In lung radiology, appearance of an air bronchogram of the superior segmental bronchus of the lower lobe because of segmental atelectasis or consolidation. (05 Mar 2000) |