Tubular organ system

Fig. 10.6 (A) Stick representation of the packing of 3 in the crystal, showing the formation of directional tubular conduction pathways (B) schematic representation ofthe hierarchically organized system 3 (top) self-organization in solution and (bottom) sol-gel transcription of encoded molecular features into a hybrid heteropolysiloxane matrix [18].

Unwanted effects of sulfonamide-type diuretics (a) hypokalemia is a consequence of excessive 1C loss in the terminal segments of the distal tubules where increased amounts of Na are available for exchange with 1C (b) hyperglycemia and glycosuria (c) hyper-uricemia-increase in serum urate levels may precipitate gout in predisposed patients. Sulfonamide diuretics compete with urate for the tubular organic anion secretory system. 

Amino acids are precious components of the human organism and therefore urinary losses are small due to an efficient renal tubular reabsorption system. Because of this, and because the analytical approach is aimed at detecting catabolic... 

Two tubular secretory systems exist for the active transport of organic acids and organic bases. Many xenobiotics can find their way back into the blood via these routes. 

Excretion The primary route of excretion is through the organic acid (tubular) secretory system of the kidney (see p. 224), as well as by glomerular filtration. Patients with impaired renal function must have dosage regimens adjusted. Thus the Xyz of penicillin G can increase from a normal of 1/2 -1 hour to 10 hours in individuals with renal failure. Probenecid inhibits the secretion of penicillins. Nafcillin is primarily eliminated through the biliary route. [Note This is also the preferential route for the acylureido penicillins in cases of renal failure.]... 

It is now recognized that GSH conjugation plays a critical role in chemical-induced nephrotoxicity and, in many cases, may be responsible for selective targeting and damage to the kidney versus other organ systems (Table 1). The capacity of the kidney to process and activate GSH conjugates is extensive and results in the release of toxic species within the proximal tubular cells. For example, haloalkenes and quinones are con-... 

Aminoacidurias may be primary or secondary. Primary disease is due to an inherited enzyme defect, also called an inborn error of metabolism. The defect is located either in the pathway by which a specific amino acid is metabolized or in the specific renal tubular transport system by which the amino acid is reabsorbed. Secondary aminoaciduria is due to disease of an organ, such as the liver, which is an active site of amino acid metabolism, or to generalized renal tubular dysfunction, or to protein-energy malnutrition. Specific inborn errors of metabohsm are discussed in more detail in Chapter 55. 

The administration of tetraethylammonium (TEA) and the organic anionic phenol-sufonphthalein (PSP) can be used as indices of cationic tubular transport systems (Klaassen and Plaa 1966). However, these tests are not included in general toxicity studies. Again, these tests require administration of the compound and carefully timed sample collections (Poutsiaka et al. 1962). 

Consider the pyrolysis of a small sample of organic material in the pyrolysis zone of the tubular reactor system. At any time t the rate of evolution of gaseous volatile matter (rriv) from the pyrolyzing sample is given by ... 

Structure and physiology of the kidney glomerular filtration tubular activity selective reabsorption and secretion, often using specific carrier mechanisms carbonic anhydrase and acid-base balance. The kidney also produces, and is sensitive to, hormones actions of the hormones ADH, aldosterone and PTH the kidney as a secretory organ erythropoietin, the renin-angiotensin system vitamin D3. 

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