Correction of thiazide hyperuricemia by potassium chloride and ammonium chloride

Spatial distribution of conspecific genotypes within chimeras of the branching coral Stylophora pistillata

Chimerism is a coalescence of conspecific genotypes. Although common in nature, fundamental knowledge, such as the spatial distribution of the genotypes within chimeras, is lacking. Hence, we investigated the spatial distribution of conspecific genotypes within the brooding coral Stylophora pistillata, a common species throughout the Indo-Pacific and Red Sea. From eight gravid colonies, we collected planula larvae that settled in aggregates, forming 2–3 partner chimeras. Coral chimeras grew in situ for up to 25 months. Nine chimeras (8 kin, 1 non-related genotypes) were sectioned into 7–17 fragments (6–26 polyps/fragment), and genotyped using eight microsatellite loci. The discrimination power of each microsatellite-locus was evaluated with 330 ‘artificial chimeras,’ made by mixing DNA from three different S. pistillata genotypes in pairwise combinations. In 68% of ‘artificial chimeras,’ the second genotype was detected if it constituted 5–30% of the chimera. Analyses of S. pistillata chimeras revealed that: (a) chimerism is a long-term state; (b) conspecifics were intermixed (not separate from one another); (c) disproportionate distribution of the conspecifics occurred; (d) cryptic chimerism (chimerism not detected via a given microsatellite) existed, alluding to the underestimation of chimerism in nature. Mixed chimerism may affect ecological/physiological outcomes for a chimera, especially in clonal organisms, and challenges the concept of individuality, affecting our understanding of the unit of selection.

Uric acid metabolism in children

The renal excretion of uric acid in children differs quantitatively, and perhaps qualitatively, from that in adult humans. The younger the child, the greater the renal clearance of uric acid and the greater the excretion of uric acid expressed as mg per kg body weight. During infancy, the reduced ability to maximally concentrate the urine may protect against precipitation of uric acid crystals within the kidney. Conversely, the extremely high urinary uric concentrations places the very small infant at jeopardy during sudden increases in the filtered load of uric acid. Understanding the pharmacologic and physiologic modulators of renal uric acid clearance will allow the pediatrician to minimize the risk of uric acid nephropathy, and to understand the implications of uric acid in the serum or urine in children with fluid and electrolyte disorders. Certainly evaluation of serum and urinary uric acid concentrations is essential in any child with acute renal failure.

Plasma uric acid and plasma albumin in healthy subjects

In healthy male subjects there was a positive correlation between plasma uric acid and plasma albumin (r = 0 - 43, P less than 0 - 005, n = 49) when repeated measurements of both variables were used for each subject. Changes in plasma albumin induced by in vivo ultrafiltration were not accompanied by changes in plasma uric acid. The correlation of plasma uric acid with plasma albumin cannot be attributed to protein binding of urate. The two variables are probably related indirectly through a common association with an unknown factor or factors.

Diuretics: mechanism of action and clinical application

Despite the bewildering number of diuretics available to the physician, these drugs can be divided into 4 main groups, characterised by their site of action on sodium reabsorption in the kidney. Drugs acting on the ascending limb of the loop of Henle have a powerful but short acting diuretic effect; they include frusemide, ethacrynic acid and bumetanide. The benzothiadiazines and related compounds have a moderate diuretic action spread over a longer period, whilst the potassium-sparing diuretics, triamterene, amiloride and spironolactone, have only a weak diuretic effect but a marked ability to diminish urinary potassium excretion. The fourth group is made up of miscellaneous substances which function as vasodilator or osmotic agents. The pathogenesis of oedema formation in heart failure is outlined and a logical approach to treatment suggested. Duiretics are being increasingly used in the treatment of non-oedematous states, in particular hypertension, diabetes insipidus and hypercalciuria; their exact role in pregnancy and acute renal failure remains controversial. Side-effects can be related to their effect on electrolyte excretion and include hypokalaemia, hyponatraemia, hyperkalaemia and hyperuricaemia. The incidence of disturbed carbohydrate tolerance in previously normal individuals is low. Other less common side-effects are also discussed.