Assessment of renal function by serum creatinine and creatinine clearance: glomerular filtration rate estimated by four procedures.
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We compared creatinine concentrations in serum and urine and creatinine clearances determined by two Jaffe (Beckman's "Astra," Boehringer Mannheim Diagnostics) and two enzymatic (Kodak, Boehringer Mannheim Diagnostics) methods. Serum creatinine and creatinine clearances determined by each method were also compared with the glomerular filtration rate as measured with use of sodium [125I]iothalamate in patients with a wide range of renal function. Results between methods correlated excellently, but we saw clear method-dependent biases of up to 2.9 mg/L for serum. The highest serum creatinine values and the lowest creatinine clearances were obtained with Boehringer Mannheim Diagnostics' Jaffe method. The reciprocal of the serum creatinine and the creatinine clearance also correlated well with the glomerular filtration rate, but all methods over-estimated the glomerular filtration rates to varying degrees. Appropriate standardization of methods appears to be as important as method principle for establishing an accurate relationship between creatinine determinations and glomerular filtration rate. (+info)
Facet joint injection for low back pain. A clinical study.
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Therapeutic injection of facet joints is now widely practised, but British experience has been infrequently reported. We studied the results of injecting facet joints with a corticosteroid preparation in 50 patients suffering from the "facet syndrome". Our series included a number of extra-articular injections and these "failed injections" provide a useful control group. Results indicate that only intra-articular injections are effective; certainty of joint penetration can be ensured only by the routine use of joint arthrography. (+info)
Animal evaluation of technetium-99m triamide mercaptide complexes as potential renal imaging agents.
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Technetium-99m mercaptoacetylglycylglycylglycine (MAG3), a [99mTc]triamide mercaptide (N3S) compound has been synthesized in an attempt to obviate the stereochemistry problems associated with the diamide dimercaptide (N2S2) ligands. Because initial studies have been promising, the terminal glycine on the MAG3 compound has been varied to create a new series of N3S compounds. Twelve new N3S complexes were initially screened in mice and the more promising complexes, 99mTc mercaptoacetylgylcylglycyl-glycine [( 99mTc]MAG3), 99mTc mercaptoacetylgylcylglycyl-L-alanine [( 99mTc]MAG2-Ala), and both complexes of 99mTc mercaptoeacetylglycylglycyl-L-asparagine [( 99mTc]MAG2-Asn) and 99mTc mercaptoacetylglycylglycyl-L-glutamine [( 99mTc]MAG2-Gln), were further evaluated in rats utilizing constant infusion blood clearances, extraction efficiencies and protein binding assays. The renal excretion of all these complexes compared favorably with simultaneously administered [131I]OIH and [125I]iothalamate. The triamide mercaptide complexes represent a new ligand class for 99mTc, which may provide a variety of complexes for the evaluation of renal tubular function. (+info)
Differential renal function in unilateral renal injury: possible effects of radiopharmaceutical choice.
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An abnormal filtration fraction or a significant divergence between a kidney's ability to extract Tc-99m dimercaptosuccinic acid (DMSA) and other function parameters, such as the glomerular filtration rate (GFR) or the effective renal plasma flow (ERPF), could lead to different estimates of relative or absolute renal function, depending on the radiopharmaceutical administered. To evaluate this possible divergence, we measured the relative GFR (I-125 iothalamate), ERPF (I-131 hippurate), and Tc-99m DMSA accumulation in adult male Sprague-Dawley rats with unilateral ureteral obstruction or unilateral ischemia at various times after renal injury. The relative ERPF of the obstructed kidney was significantly greater than the relative GFR at all time periods studied; significant but less dramatic differences were noted comparing DMSA with GFR in obstruction and DMSA and ERPF with GFR in ischemia. In evaluating renal disease, it is important to consider the functional parameter reflected by the administered radiopharmaceutical as well as the underlying disease state. (+info)
Mechanism of renal concentration of technetium-99m glucoheptonate.
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Seventy female Sprague-Dawley rats were studied to determine the mechanism of tubular localization and the effects of commonly encountered changes in hydration and acid-base balance on renal uptake and urinary excretion of technetium-99m glucoheptonate ([99mTc]GHA). The in-vivo protein binding and protein-free plasma clearance of [99mTc]GHA also were quantitated. Twenty additional rats were studied to determine the effects of PAH competition and probenecid blockade on renal uptake of [99mTc]dimercaptosuccinic acid (DMSA) in comparison with their effects on [99mTc]GHA localization. Kidney uptake of [99mTc]GHA averaged 11.17 +/- 0.49 (s.e.)% of the injected dose in control animals. This varied slightly among groups but was significantly reduced by probenecid blockade and para-aminohippuric acid (PAH) competition to 4.08 +/- 0.55 (p less than 0.005) and 2.39 +/- 0.14 (p less than 0.005), respectively. Technetium-99m DMSA was not affected in its renal accumulation by these maneuvers. The total plasma clearance of [99mTc]GHA was lower than iodine-125(125I)iothalamate but the clearance of the protein free supernate was higher, raising a possibility of some tubular secretion. Acidification of the urine which has been shown to reduce [99mTc]DMSA uptake appeared to have no effect on [99mTc]GHA. Hepatic uptake was minimal in all groups averaging less than 1% injected dose. These data demonstrate that renal accumulation of [99mTc]GHA is blocked by probenecid and PAH suggesting that it is actively concentrated in the proximal tubule by enzyme systems similar to those involved in PAH and hippuran transport. It appears that [99mTc]GHA uptake measures a different aspect of kidney function than [99mTc]DMSA. (+info)
Radioisotopic measurement of glomerular filtration rate in severe chronic renal failure.
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In order to determine the best method for routine measurement of glomerular filtration rate (GFR) in severe renal failure, we compared simultaneously the urinary clearances of [99mTc] diethylenetriaminepentaacetic acid (DTPA) (UD), [125I]iothalamate (UI), 24-hr creatinine clearance (UC) and plasma clearance of [99mTc]DTPA (PD), based on three plasma samples. In 60 studies in 22 patients with serum creatinine values of 2 to 8 mg/dl, UD and UI were almost identical: UD = 0.358 +/- 0.976 UI +/- 0.87 ml/min, r = 0.990. However, PD overestimated UD by a large and variable extent: PD = 11.3 +/- 0.843 UD +/- 5.5 ml/min, r = 0.694, and was inconsistent in sequential measurements in individual patients. UC also overestimated urinary isotope clearance: UC = 4.2 + 0.95 UI +/- 3.9 ml/min, r = 0.865. Sequential measurements of GFR in five patients with severe but stable renal failure (mean GFR 5.9 ml/min) showed an average standard deviation of only 0.83 ml/min. Thus both UD and UI appear to be reliable and precise measures of GFR in severe renal failure. (+info)
Contrast-enhanced lesions on computerised tomography in multiple sclerosis.
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Two patients are described in whom computerised tomography revealed contrast-enhanced lesions in the early stages of multiple sclerosis. Such lesions may be differentiated from tumours by their transient nature, lack of space-occupying effect, and localisation in the white matter. Contrast enhancement in demyelinating disease is probably related to local breakdown of the blood-brain barrier. (+info)
Acute renal failure with selective medullary injury in the rat.
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Since human acute renal failure (ARF) is frequently the result of multiple rather than single insults, we used a combination of treatments to induce ARF in rats. Uninephrectomized, salt-depleted rats injected with indomethacin developed ARF after administration of radiocontrast. After 24 h, the plasma creatine rose from 103 +/- 3 to 211 +/- 22 mumol/liter (mean +/- SE) and the creatinine clearance dropped from 0.7 +/- 0.1 to 0.2 +/- 0.04 ml/min (P less than 0.001). Severe injury was confined to the outer medulla and comprised necrosis of medullary thick ascending limbs (mTALs), tubular collapse, and casts. Other nephron segments were free of damage except for the proximal convoluted tubules which showed vacuole formation originating from lateral limiting membranes that resembled changes reported in human contrast nephropathy. Cell damage to mTALs included mitochondrial swelling, nuclear pyknosis, and cytoplasmic disruption with superimposed calcification; these changes were most severe in the deepest areas of the outer medulla, away from vasa recta in zones remote from oxygen supply. The fraction of mTALs with severe damage was 30 +/- 7% (range 2-68) and the extent of injury was correlated with a rise in plasma creatinine (r = 0.8, P less than 0.001). Thus, the nature of mTAL injury was similar to the selective lesions observed in isolated kidneys perfused with cell-free medium and was shown to derive from an imbalance between high oxygen demand by actively transporting mTALs and the meager oxygen supply to the renal medulla. Combined multiple renal insults in the rat produce ARF that resembles the clinical syndrome of contrast nephropathy and is characterized by selective mTAL injury conditioned by medullary hypoxia. (+info)