Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “IOTHALAMIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMed1996

Measurement of glomerular filtration rate using nonradioactive Iohexol: comparison of two one-compartment models.

Radioisotopic methods for the determination of the glomerular filtration rate (GFR) are highly accurate but require the collection of multiple blood and urine samples and are costly to perform due to personnel, material, and analysis costs. Nonradioactive methods of GFR determination have the potential of minimizing procedure costs while preserving accuracy. We determined the GFR simultaneously by 125I-iothalamate and nonradioactive iohexol clearance methods in 41 adults. The study group consisted of 54% males, with a mean age of 50.7 (range 28-79) years and a mean GFR by 125I-iothalamate clearance of 66.5 +/- 28.3 (range 10-118) ml/min. The iohexol concentrations were measured by a simplified high-performance liquid chromatography method that did not require sample preparation. The iohexol plasma clearance was calculated by both a new one-compartment model as well as by Jacobsson's one-compartment model. Using Jacobsson's single-sample model and data from the 240-min point, there was an excellent correlation between 125 I-iothalamate and nonradioactive iohexol clearance values: r2 = 0.95, standard error of the estimate = 11.4 ml/min, and intrapatient coefficient of variation = 16.9%. However, this formula tended to overestimate GFRs < 30 ml/min and to underestimate GFRs > 80 ml/min. The new one-compartment model is a modification of Bubeck's model, originally used for the determination of renal plasma blood flow. Using this modified model, there was an excellent correlation between 125I-iothalamate and nonradioactive iohexol clearance values at all levels of GFR tested: r2 = 0.95, standard error of the estimate = 9.2 ml/min, and intrapatient coefficient of variation = 13.7%. In conclusion, the determination of the plasma clearance of iohexol by a nonradioactive technique and a monoexponential model is a simple and accurate method of determining the GFR in patients with varying degrees of renal impairment.

Adult↗
PubMed1979

125I-iothalamate and creatinine clearances in patients with chronic renal diseases.

In 196 adult patients with chronic renal disease or primary hypertension, the evaluation of glomerular filtration rate (GFR) by means of creatinine clearance, 'predicted' creatinine clearance and [125I]-iothalamate clearance was performed. Iothalamate clearance was evaluated after subcutaneous injection of the substance . In patients with normal or upper borderline plasma creatinine values, the iothalamate clearance ranged from 44 to 117 ml/min/1.73 m2 and the overestimation of GFR from creatinine clearance was negligible. In patients with mild or advanced renal failure, the overestimation of GFR from creatinine clearance increased up to 18 and 32%, respectively. The clinical usefulness of iothalamate clearance is evident especially in patients with mild renal failure, in whom an accurate evaluation of GFR is often important for a correct dietary and therapeutic approach.

Adolescent↗
PubMed1981

Prediction of glomerular filtration rate by serum creatinine and beta 2-microglobulin.

The reciprocal of serum creatinine concentration (1/Cr) is often used to predict glomerular filtration rate (GFR). Serum creatinine also varies with age, size, and muscle mass, and so it may inaccurately estimate GFR. The reciprocal of serum beta 2-microglobulin (1/beta 2mu) has been proposed as an alternative estimator of GFR. This study compares 1/Cr and 1/beta 2mu as predictors of GFR as measured by 125I-iothalamate clearance (CIOT) and creatinine clearance (CCr) in 29 subjects with a wide range of age, size and kidney function, and including 12 chronic hemodialysis patients. 1/beta 2mu was a better predictor of CIOT (r=0.90) and CCr (r=0.87) than 1/Cr (r=0.50 and 0.78) was. In fact, in the nondialysis population, 1/beta 2mu predicted CIOT (r=0.86) about as well as CCr predicted CIOT (r=0.87). Beta 2mu was less dependent on body size than Cr and unlike Cr, was not influenced by dialysis and did increase as GFR decreased with age. Beta 2mu can be useful as an alternative clinical estimate of GFR, particularly when Cr is considerably influenced by factors other than renal function.

Adult↗
PubMed1987

Protection against acute renal failure by prior acute renal failure: differences between myohemoglobinuric and ischemic models.

Prior acute renal failure (ARF) induced by either glycerol (G) or mercury provides protection against rechallenge with the same agent or the other. To ascertain whether the widely employed ischemic renal failure model also shares a similar pathogenesis, two protocols were designed. In the first protocol, unilaterally nephrectomized rats with or without a prior episode of G-induced ARF two weeks previously were subjected to an ischemic insult [60-min total left renal artery clamp (LRAC)]. At 24 or 48 h after LRAC there was no difference in renal function in the rats with or without prior ARF. In the second protocol the sequence of G and ischemia was reversed. In rats having undergone LRAC two weeks prior to G, glomerular filtration rate was virtually identical from the right (control) and left (prior ARF) kidney (right, 138 +/- 30; left, 101 +/- 22 microliter/min/100 g body weight), and not different from rats receiving G alone. We conclude that protection against ARF conferred by prior insult is not a feature of all models.

Acute Kidney Injury↗
PubMed1996

Gadodiamide in renal transplant patients: effects on renal function and usefulness as a glomerular filtration rate marker.

Gadodiamide at a dose of 0.1 mmol/kg was administered intravenously to 10 renal transplanted patients with stable, impaired, or slowly deteriorating renal function (serum creatinine 194-362 mumol/l). The patients were referred for contrast medium enhanced magnetic resonance imaging to rule out possible graft circulation abnormalities. The excretion of gadodiamide in urine was prolonged as compared with healthy controls. After 120 h 92% of the injected dose was excreted in urine and only 0.4% in faeces. The plasma clearance of gadodiamide was 28.6 +/- (SD) 5.5 ml/min (n = 10), and the renal clearance (0-72 h) was 26.3 ml/min. The renal clearance of 125I-iothalamate for the same time period was 27.9 +/- 5.3 ml/min. Thus, gadodiamide is eliminated by glomerular filtration also in renal transplant patients with moderately to severe impaired renal function, and gadodiamide clearance may serve as an alternative marker for the determination of the glomerular filtration rate. Serum values of creatinine and beta(2)-microglobulin and creatinine clearance were unchanged by gadodiamide and neither was the urinary enzyme excretion significantly changed. These results suggest that the renal tolerance to gadodiamide is good also in renal transplant patients with impaired renal function.

Adult↗
PubMed1997

Meglumine gadoterate: a new safe radiocontrast medium for endoscopic retrograde cholangiopancreatography?

The radiocontrast substance meglumine gadoterate (MG) is used in magnetic resonance imaging. It is characterized by its low rate of adverse drug reactions. In an open study we tested whether MG is useful in endoscopic retrograde cholangiopancreatography. The patients received in sequence MG and ioxotalamate. MG, in contrast to ioxotalamate, failed to visualize the proximal pancreatic and peripheral intrahepatic ducts. Thus, MG is not useful in routine endoscopic retrograde cholangiopancreatography. However, in patients with a history of severe allergic reactions to conventional contrast media, MG may be recommended when pathological findings of the extrahepatic bile duct or the area of the pancreatic head are suspected.

Adolescent↗
PubMed1979

In vitro histamine and serotonin release studies in atopic dermatitis.

6 patients suffering from severe atopic dermatitis with high serum IgE were investigated. 3 of the patients had elevated plasma histamine levels (1.5-2.0 ng/ml). Compared to 9 nonatopic normal volunteers, the patient showed increased in vitro histamine release from peripheral leukocytes after stimulation with iothalamate and methacholine: while there was no significant histamine release at a methacholine concentration of 10(-4) M in normals, 4 of the patients with atopic dermatitis showed measurable histamine release under these conditions in vitro. The uptake of radiolabeled serotonin by platelets in vitro was decreased in 2 of the patients. There was no significant difference in serotonin release induced in vitro by different concentrations of thrombin, epinephrine and methacholine; 2 patients showed an increased platelet release reaction after iodipamide stimulation. It is concluded that a general tendency to release vasoactive mediators, even after 'nonimmunologic' stimulation, might play a role in the pathogenesis of atopic dermatitis.

Adult↗
PubMed1992

Three-dimensional computed tomographic imaging of the pelvicaliceal system: analysis of factors influencing image quality.

We analyzed 3-dimensional (3D) computed tomographic images of the pelvicaliceal system obtained in 25 patients after opacification of the collecting system by retrograde ureteric or intravenous (IV) infusion of sodium iothalamate. 3D images were reconstructed using the data from nonoverlapping 5-mm sections taken on an Elscint 2400 scanner. Factors contributing to poor image quality were: artifacts caused by contrast in the collecting tubules, underfilling or overdistension of the pelvicaliceal system with contrast, movement of the patient and severe hydronephrosis. Satisfactory 3D images of the pelvicaliceal system can be obtained by retrograde ureteric infusion of 5% w/v sodium iothalamate at 20 cm H2O, or by IV injection of 50 ml of 70% w/v sodium iothalamate. Abdominal compression should be applied 10-15 min after the IV injection of contrast, and the computed tomographic examination should commence 20-30 min after the injection. It is imperative that the patient lie completely still and breathe normally to avoid movement of the kidneys. 3D computed tomographic imaging of the pelvicaliceal system may become a valuable adjunct to the preoperative planning and performance of percutaneous nephrolithotomy.

Adolescent↗
PubMedDate not supplied

Control of arterial pressure and renal function during glucocorticoid excess in dogs.

This study was designed to investigate the long-term effects of glucocorticoids on the control of mean arterial pressure (MAP) and renal function. Infusion of 10 mg/day of methylprednisolone (MP), a glucocorticoid with minimal mineralocorticoid activity, for 10 days in six intact conscious dogs maintained on a sodium intake of 78 mEq/day resulted in a decrease in MAP from 98 +/- 1 to 89 +/- 2 mm Hg, a decrease in sodium iothalamate space to 89 +/- 2% of control, and a marked increase in glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and urinary sodium excretion. Chronic infusion of MP at doses of 2--800 mg/day in four dogs maintained on low (5 mEq/day) or high sodium intakes (160--223 mEq/day) also caused increases in GFR and ERPF, as well as natriuresis and decreased sodium iothalamate space, while causing either no change or a slight reduction in MAP. To determine whether glucocorticoids potentiate the chronic effects of angiotensin II (AII) on MAP and renal function, MP was infused in dogs undergoing AII infusion (5 ng/kg/min). During AII hypertension, chronic infusion of 5 or 10 mg/day of MP also resulted in a marked renal vasodilation, natriuresis, and reductions in sodium iothalamate space, while causing small reductions in MAP. Thus, we found no evidence that chronic glucocorticoid excess causes hypertension in dogs, or that glucocorticoids potentiate the blood pressure or renal effects of AII. Instead, glucocorticoids tended to reduce MAP, probably because of chronic renal vasodilation, increased excretion of sodium, and volume depletion.

Aldosterone↗
PubMed2006

Drawbacks and prognostic value of formulas estimating renal function in patients with chronic heart failure and systolic dysfunction.

BACKGROUND: Renal function is an important risk marker for morbidity and mortality in chronic heart failure (CHF) and is often estimated with the use of creatinine-based formulas. However, these formulas have never been validated in a wide range of CHF patients. We validated 3 commonly used formulas estimating glomerular filtration rate (GFR) with true GFR in CHF patients. Furthermore, we compared the prognostic value of these formulas for cardiovascular outcome with that of true GFR during 12 months of follow-up. METHODS AND RESULTS: In 110 CHF patients (age, 57+/-11.7 years; left ventricular ejection fraction, 0.27+/-0.09; NYHA class, 2.5+/-0.9), we measured 125I-iothalamate clearance. Cockcroft-Gault (GFR(cg)), Modification of Diet in Renal Disease (MDRD), and simplified MDRD (sMDRD) equations were used as creatinine-based renal function estimations. Furthermore, 24-hour creatinine clearance (CrCl) was determined. CrCl and GFR(cg) were the most accurate. MDRD was most precise formula, although it was also highly biased. All formulas overestimated in the lower ranges and underestimated in the upper ranges of the GFR corrected for body surface area. The predictive performance of the formulas was best in severe CHF (NYHA classes III and IV). The prognostic value of CrCl and MDRD for cardiovascular outcome was comparable to that of GFR, the sMDRD was slightly less, and the GFR(cg) had a significantly worse prognostic value. CONCLUSIONS: In the more severe ranges of CHF, creatinine-based formulas and CrCl corrected for body surface area appeared to be more precise and accurate in estimating true GFR corrected for body surface area. The MDRD formula is the most precise and has a good prognostic value, whereas the sMDRD is slightly less accurate but uses fewer parameters, which makes this formula a practical alternative in clinical practice.

Aged↗
PubMed1972

Renal tubular permeability during increased intrarenal pressure.

Renal tubular permeability was studied by microinjection techniques during increased intrarenal pressure in anesthetized diuretic rats. Intrarenal pressure, as evidenced by intratubular pressure (ITP), was increased by elevation of ureteral pressure, partial renal venous constriction, or massive saline diuresis. Various combinations of radioactive inulin, creatinine, mannitol, sucrose, and iothalamate in isotonic saline were microinjected into superficial proximal and distal convolutions, and recovery of the isotopes was measured in the urine. Inulin was completely recovered in the urine from the injected kidney at both normal and elevated ITP. Creatinine, mannitol, sucrose, and iothalamate were also completely recovered at normal ITP, but recoveries were significantly lower, averaging 73, 85, 89, and 85%, respectively, after early proximal injection when proximal ITP was increased to 30+/-2 mm Hg by elevation of ureteral pressure. Since transit time is prolonged under these conditions, mannitol recovery was also studied during aortic constriction, which prolongs transit time but lowers ITP. Recovery was complete. A significant loss of mannitol was observed during massive saline diuresis, which shortens transit time but increases ITP. During renal venous constriction producing a proximal ITP of 30+/-2 mm Hg, mannitol recovery was significantly less than 100% even after microinjection into distal convolutions, but the loss was greater injection at more proximal puncture sites. Mannitol recovery was complete during elevation of ureteral pressure in the contralateral kidney. These studies demonstrate a change in the permeability characteristics of all major segments of the renal tubule during elevation of intrarenal pressure. This change is rapidly reversible and does not appear to be due to a humoral factor which gains access to the general circulation.

Animals↗
PubMed1975

A functional comparison of the cortical collecting tubule and the distal convoluted tubule.

Electrical and permeability features of the distal convoluted tubule (DCT) and the cortical collecting tubule (CCT) were examined using the technique in which isolated segments of rabbit tubules were perfused in vitro. When rabbits were given a regular diet and tubules were perfused and bathed in artificial solutions simulating plasma ultrafiltrate, the potential difference (PD) was +3.7 plus or minus 1.9 mV in the CCT and -40.4 plus or minus 2.8 mV in the DCT. When rabbits were given a low sodium, high potassium diet plus i.m. deoxycorticosterone acetate (DOCA) (1 mg/kg per day), the PD in both the CCT (-30.8 plus or minus 3.9 mV) and the DCT (-33.8 plus or minus 5.5 mV) was negative. The PD in the CCT was quantitatively similar to that of diet plus DOCA when animals were given DOCA alone. The PD in both segments was inhibited by ouabain (10-minus 5 M) in the bath or by amiloride (10-minus 5 M) in the perfusate. Addition of vasopressin (200 muU/ml) to the bath caused a gradual decline of PD to zero in the CCT but failed to produce a potential response in the DCT. Osmotic water permeability was essentially zero in both segments in the absence of vasopressin. After addition of the vasopressin to the bath, osmotic water permeability in the DCT remained zero but increased to 71.9 plus or minus 25.5 X 10-minus 7 cm/s per atm in the CCT. We conclude that both segments are similar in that each possesses an electrogenic transport process but that these segments differ in that: (a) the CCT requires either exogenous or endogenous mineralocorticoid to maintain a maximal negative PD, whereas the PD in the DCT appears to be independent of mineralocorticoid effect; and (b) the CCT responds to vasopressin with a marked rise in water permeability, whereas the DCT is impermeable to water before and after addition of vasopressin.

Adrenal Cortex Hormones↗
PubMed1975

A natriuretic principle derived from kidney tissue of volume-expanded rats;.

Homogenates of kidneys from hydropenic and volume-expanded rats were subjected to gel filtration with Sephadex G-25. A fraction of the eluate coincident with the fourth UV peak was injected into the aorta of rats with one kidney excluded. A fraction eluting before the albumin peak was utilized as a control. Significant natriuresis and diuresis were observed after infusion of the fraction obtained from volume-expanded kidneys but not after infusion of the fraction from hydropenic kidneys or the control fraction. The natriuresis occurred in in the absence of changes in mean blood pressure, hematocrit, plasma sodium and potassium, glomerular filtration rate, and potassium excretion. The response was apparent immediately after infusion and persisted for up to 150 min. These results verify the existence of a low molecular weight natriuretic substance which may be preferentially bound to the kidney after its volume-stimulated release into the circulation.

Animals↗
PubMed1988

Acute renal failure with selective medullary injury in the rat.

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.

Acute Kidney Injury↗