Measurement of GFR with a single intravenous injection of nonradioactive iothalamate.
Explore the source record for details and available documents.
Edetic Acid↗
Biomedical subjects
P Ruggenenti
Publications and source records attributed to P Ruggenenti.
Daily renal hypoperfusion induced by cyclosporine in patients with renal transplantation.
A variety of side effects are associated with the use of cyclosporine, the most relevant of which remains the renal toxicity. We did parallel studies on cyclosporine pharmacokinetics and renal function in patients who had a recent kidney transplant and were given cyclosporine as a part of their immunosuppressive therapy. Seven consecutive renal transplant patients were studied at the end of a month of treatment while on different oral cyclosporine doses (5, 3.5, 2.5, or 1.5 mg/kg, twice a day, respectively). Cyclosporine pharmacokinetics profiles and renal function parameters (GFR and renal plasma flow [RPF], as inulin and p-amino hippurate clearances, respectively) were determined before and over a 12-hr period after each single dose of cyclosporine. Plasma levels and urinary excretion rate of endothelin were also studied before and after the highest cyclosporine dose (5 mg/kg). Mean trough levels, area under the curve values, and maximum concentration of blood cyclosporine were comparable after 5 and 3.5 mg/kg cyclosporine and decreased in a dose-dependent manner after the lower doses (2.5 and 1.5 mg/kg). In the same patients GFR declined on average 63%, 53%, 35%, and 18%, 2-4 hr after maximum cyclosporine concentration was reached. As blood levels of cyclosporine returned to trough, GFR progressively increased to baseline. Similar results were found for RPF; 5 mg/kg cyclosporine did not modify endothelin plasma levels. By contrast, urinary excretion of the peptide increased significantly (P less than 0.01) in the 6 hr that followed cyclosporine administration and returned within the normal range in the subsequent 6 hr. Following each oral administration of cyclosporine, 2-4 hr after peak blood concentration was reached, patients showed renal hypoperfusion, transient and rapidly reversible. This was associated with an increased urinary endothelin excretion rate that was also transient. It is speculated that an excessive renal synthesis of endothelin is the cause of the daily renal hypoperfusion observed in patients with renal transplants given cyclosporine.
Adult↗
Renal function at hospital admission as a prognostic factor in adult hemolytic uremic syndrome. The Italian Registry of Haemolytic Uremic Syndrome.
The clinical records of adult patients with a diagnosis of hemolytic uremic syndrome were retrospectively reviewed with the aim of evaluating the long-term outcome of renal function. The setting is the Italian Registry of Haemolytic Uraemic Syndrome, with which 13 Nephrology Centers have participated. Clinical and laboratory data of 43 patients with hemolytic uremic syndrome were evaluated. The mean age at onset was 34.3 +/- 18.3 yr. Men and women were equally affected. No seasonal trend in presentation was observed. In 20 patients, hemolytic uremic syndrome was primitive, whereas in 23, it was associated with another disease (cancer, preeclampsia, malignant hypertension, vasculitides). Gastrointestinal symptoms were the most frequently observed prodromes. Thirty (70%) patients required dialysis during the acute phase of the disease. Six patients died during the acute phase of the disease, and one died later after discharge (overall mortality, 16%). After 1 yr of follow-up, 11 (26%) patients had recovered a normal renal function, 14 (33%) had hypertension and/or renal insufficiency, and 11 (26%) were on regular dialysis. When prognostic factors of survival and recovery of renal function were considered, it was found that older age was associated with higher mortality in the acute phase, whereas severe renal involvement at the onset of the disease (as expressed by elevated serum creatinine) was associated with a long-term unfavorable prognosis.
Adolescent↗
Plasma manipulation in hemolytic uremic syndrome and thrombotic thrombocytopenic purpura.
The hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) are syndromes of microangiopathic hemolytic anemia dominated by renal failure in children and by neurological signs in adults. Microvascular thrombosis is the typical lesion and endothelial injury is likely the initial event. Over the last 40 years, the prognosis has significantly improved, probably as the result of better supportive management of anemia, renal failure, hypertension, and electrolyte and water imbalances, but still remains poor in adults with renal arteriolar thrombosis and neurological involvement. Many specific therapies have been used and, based on reports of a few cases, a consensus has been reached empirically that recognizes antiplatelet agents and plasma manipulation as the most appropriate therapy for adult HUS and TTP. Their effectiveness, however, still remains to be formally tested in prospective controlled trials. Recently, we saw a 23-year-old man with a history of recurrent episodes of HUS in childhood and of TTP since the age of 21. HUS always disappeared following blood transfusions, whereas prompt remissions of the episodes of TTP were obtained with plasma exchange. In order to avoid the use of plasma, alternate forms of therapy were tried. However, aspirin (50 mg/day), prednisone (1 mg/kg bw/d), and human immunoglobulins (0.5 mg/kg/d) were ineffective, and plasma exchange was needed to obtain remission. During two more recent relapses, fresh-frozen plasma was infused as the initial therapy and produced a complete remission within few days, thus preventing the need for plasma exchange. During the last relapse, plasma exchange with albumin and saline failed to induce remission and plasma infusion was required.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
High-performance liquid chromatographic determination of iothalamic acid in human plasma and urine.
A simple, rapid and sensitive method for the determination of iothalamic acid (IA) in both plasma and urine is reported. After extraction with ethyl acetate, IA was determined by strong anion-exchange high-performance liquid chromatography with ultraviolet detection at 254 nm. The lower limit of detection was 0.5 micrograms/ml. The average recovery was 73 and 57% from plasma and urine, respectively. Linearity was found over the investigated concentration range (up to 500 micrograms/ml for plasma and up to 10.0 mg/ml for urine). The reproducibility of the technique was good (coefficient of variation less than 6%) as was the precision and accuracy (coefficient of variation less than 2.5%). No interference from endogenous substances or any of the common drugs tested was found.
Acetates↗
Prevention and treatment of pregnancy-associated hypertension: what have we learned in the last 10 years?
High blood pressure (BP) complicates approximately 10% of all pregnancies. Hypertension in pregnancy falls into four categories: (1) preeclampsia-eclampsia, (2) chronic hypertension of whatever cause, (3) preeclampsia-eclampsia superimposed to chronic hypertension or renal disease, and (4) transient or late hypertension (gestational hypertension). Preeclampsia, the association of hypertension, proteinuria, and edema, accounts for more than 50% of all the hypertensive disorders of pregnancy and is a major cause of fetal and maternal morbidity and mortality. Unfortunately, distinguishing between preeclampsia and other causes of hypertension on clinical grounds can be difficult because of the lack of specific tests for differential diagnosis. Increased vascular resistance has been claimed as the primary cause of preeclampsia; however, a variable hemodynamic profile with relatively high cardiac outputs, normal filling pressures, and inappropriately high systemic vascular resistances is now reported by most investigators. Imbalance between vasodilator and vasoconstrictor eicosanoids may account for platelet activation and increased responsiveness to pressor peptides. Altered prostacyclin (PGI2) to thromboxane A2 (TxA2) ratio in maternal uteroplacental vascular bed may favor local platelet activation and vasoconstriction contributing to placental insufficiency and fetal distress. Alternatively, recent evidence seems to suggest that fetal umbilical placental circulation may be the site of the primary vascular injury. Whether low-dose aspirin prevents preeclampsia because it inhibits the excessive maternal TxA2 or whether the partial inhibition of fetal TxA2 is also of therapeutic value remains to be established. Treatment of severe hypertension in pregnancy is probably important to prevent cardiac failure or cerebrovascular accidents in the mother. The need for pharmacological therapy of mild to moderate hypertension is still debated, since no formal studies are available to clarify whether pharmacological treatment in such instances effectively reduces maternal or fetal risk. For the treatment of preeclampsia, hydralazine and nifedipine may be used when delivery is not applicable. Labetalol and diazoxide are effective for hypertensive emergencies. Life-threatening hypertension that does not respond to more conventional therapy is an indication for the use of sodium nitroprusside. For chronic hypertension, alpha-methyldopa remains the treatment of choice; if ineffective, hydralazine or beta-blockers are suitable. Effectiveness and safety of other molecules remain elusive.
Antihypertensive Agents↗
Angiotensin converting enzyme inhibition improves glomerular size-selectivity in IgA nephropathy.
Clearances of uncharged dextrans of broad size distribution were used to evaluate the effects of a 30 day course of enalapril on glomerular barrier function in 10 patients with IgA nephropathy and proteinuria (from 1.4 to 5.6 g/day). Dextran clearance experiments were repeated three times: before enalapril therapy, after 30 days of enalapril and again 30 days after enalapril withdrawal. GFR, but not RPF, was significantly reduced by enalapril (basal 38.3 +/- 11.9, enalapril 30.2 +/- 12.6 ml/min/1.73 m2) and returned to basal values after enalapril withdrawal. Urinary protein excretion and fractional clearance of albumin were both significantly reduced by enalapril (basal 2.3 +/- 1.1 g/day and 102 +/- 90 x 10(-5), enalapril 1.2 +/- 0.6 g/day and 51 +/- 23 x 10(-5), respectively) and returned to basal values after enalapril withdrawal. Transglomerular passage of large dextrans (radii 54 to 62 A), but not of lower size (26 to 42 A) were significantly lowered by enalapril. When enalapril was withdrawn the dextran-sieving profile returned comparable to the baseline levels. A theoretical analysis of dextran-sieving profiles indicated that enalapril lowered the radius of largest membrane pores. This effect was independent from glomerular hemodynamic changes. We conclude that angiotensin converting enzyme inhibitors (CEI) in humans with IgA nephropathy reduces urinary protein excretion by a primary action on the intrinsic glomerular membrane properties enhancing barrier size-selective function. The hypofiltration associated with enalapril therapy in these patients, which was eliminated by its withdrawal, has to be taken into account as a possible undesired effect of CEI in long-term treatment.
Adult↗
Nature and extent of glomerular injury induced by cyclosporine in heart transplant patients.
We sought to clarify whether low-dose cyclosporine (5.0 +/- 2.2 mg/kg/day) given for more than two years to prevent cardiac graft rejection induced glomerular injury and to quantify the extent of the lesions. After renal hemodynamic studies, renal biopsy specimens were obtained from 10 patients on cyclosporine and analyzed by a novel morphometric technique consisting of a tridimensional reconstruction of the glomerular tuft. Autopsy kidney specimens from three patients with no clinical history of renal disease, and from four patients who died with dilatative cardiomyopathy served as controls. The glomerular filtration rate and renal plasma flow were significantly depressed below normal values in transplant recipients given cyclosporine, averaging 35 +/- 8 and 325 +/- 94 ml/min/1.73 m2, respectively. Conventional light microscopy of specimens from controls and from patients who died with dilatative cardiomyopathy did not reveal renal structural abnormalities. By contrast kidney specimens from cyclosporine-treated patients had obliterative arteriolopathy and ischemic-type changes, with thickening and wrinkling of glomerular capillary wall. Morphometrical analysis of 28 control glomeruli and 40 glomeruli from patients with dilatative cardiomyopathy showed glomerular capillary tuft volumes (VCT) ranging between 1.2 and 2.3 microns 3 x 10(-6), whereas of 102 glomeruli from cyclosporine-treated patients 42.1% had VCT lower than 1.2 microns 3 x 10(-6) and 24.4% VCT higher than 2.3 microns 3 x 10(-6).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
A cathepsin-like cysteine proteinase proaggregating activity in thrombotic thrombocytopenic purpura.
The platelet aggregating activity (PAA) of serum and plasma from thrombotic thrombocytopenic purpura (TTP, eight patients) and haemolytic uraemic syndrome (HUS, three patients) was investigated. Sample-induced aggregation of washed platelets and the parallel 3H-serotonin release were studied both in the presence and the absence of purified von Willebrand factor (vWF) or defibrinated cryoprecipitate, according to Kelton et al (1987). All the samples but two were positive in the test, vWF being indispensable for aggregation in all but two of the active cases. Samples from five patients during remission were ineffective under the same conditions, as were 14 controls from healthy donors. An inhibition study using four cysteine proteinase inhibitors (1 mM iodoacetamide, 0.5 mM E-64, 0.1 mM antipain and 0.1 mM leupeptin) and two serine proteinase inhibitors (200 U/ml aprotinin and 0.2 U/ml hirudin) confirmed that TTP/HUS's PAA behaved enzymatically as a cysteine proteinase, as described (Murphy et al, 1987a). These results were confirmed on a protein preparation obtained from pooled plasmas after Al(OH)3 adsorption, ammonium sulphate precipitation, binding to and elution from a p-(chloromercuri)benzoate (PCMB) affinity resin. To further characterize this activity we investigated whether it was a calcium-dependent neutral protease or a lysosomal cathepsin by testing the sensitivity to a series of peptidyl diazomethyl ketones, synthetic inhibitors specifically designed for cysteine proteinases. We confirm here the presence of a circulating platelet aggregating cysteine proteinase in TTP/HUS and provide evidence for the first time that this activity behaves like a lysosomal cathepsin.
Adolescent↗
Glomerular response to hyperglycemia in human diabetic nephropathy.
We have studied the effect of acute hyperglycemia on glomerular function in seven insulin-dependent diabetics with overt nephropathy during hyperglycemic or euglycemic clamp. In all patients glomerular filtration rate (GFR) was higher during hyperglycemia than during euglycemia (35.0 +/- 15.5 vs. 21.4 +/- 10.3 ml.min-1.1.73 m-2, P less than 0.01), whereas renal plasma flow did not change significantly. To establish which determinant of GFR is altered by hyperglycemia, fractional clearances of neutral dextrans of graded molecular size were determined in both glycemic states, and data were analyzed by a theoretical model of hindered transport of macromolecules through a porous membrane. Hyperglycemia significantly increased sieving coefficients of small dextran molecules (28-40 A in radius), whereas fractional clearances of large macromolecules (greater than 44 A) did not change. Theoretical analysis suggested that the ultrafiltration coefficient (Kf) and membrane permeability to small dextrans (less than 40 A) increased in hyperglycemia in respect to euglycemia. Because these results have been obtained in patients with severe renal failure and hypertension, our conclusions do not necessarily apply to the early phase of diabetic nephropathy.
Body Water↗
Failure of prostacyclin to improve peripheral arterial disease in dialysis patients.
Explore the source record for details and available documents.
Aged↗
Thrombotic thrombocytopenic purpura and related disorders.
This article provides us with background information on the disease. Clinical features, variants and classification, laboratory findings, and pathology are discussed. Knowledge of the disease's pathogenesis has increased recently and specific causes discussed are predisposing factors, triggering agents, endothelial damage, defective PGI2 bioavailability, FVIII/vWF multimeric structure abnormalities, platelet activation, and hemolytic anemia. Proposed specific therapies discussed are steroids, heparin, antiplatelet agents, prostacyclin, splenectomy, immunosuppressive agents, plasma infusion, and plasma exchange.
Adolescent↗
Enhanced proteolysis of plasma von Willebrand factor in thrombotic thrombocytopenic purpura and the hemolytic uremic syndrome.
To examine whether enhanced in vivo proteolysis of von Willebrand factor (vWF) would account for the reported loss of larger multimers in acute thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), we studied eight patients with acute TTP/HUS whose blood samples were collected into an anticoagulant containing a cocktail of protease inhibitors to impede in vitro proteolysis. In all, enhanced proteolytic degradation of vWF was expressed as a relative decrease in the intact 225-Kd subunit of vWF and a relative increase in the 176-Kd fragment. However, instead of the loss of larger forms of normal multimers reported by other investigators, the plasma of all but one of our patients (whether they had TTP or HUS) contained a set of larger than normal (supranormal) multimers. Hence, although proteolytic fragmentation of vWF was enhanced during acute TTP/HUS, this phenomenon was not associated with the loss of larger multimers. In the five patients who survived the acute disease and underwent plasma exchange (three with HUS and two with chronic relapsing TTP), subunits and fragments returned to normal values, and supranormal multimers were no longer detected in plasma. In conclusion, even though vWF proteolysis is enhanced in acute TTP/HUS, it does not lead to loss of larger multimers.
Adolescent↗
Are "routine" clinical and laboratory examinations of any help in the treatment of chronic hemodialysis patients?
The relevance of routine physical examinations, laboratory tests, and x-rays in guiding therapeutic decisions was investigated in 54 patients on hemodialysis. Patients were observed for 1 year, while recording all therapeutic interventions and tracing the procedures that had determined them. In no case did a variation in treatment follow the routine physical examination of a patient who was not symptomatic or already signaled for BP or dialytic problems by the hemodialysis nurses. A number of major therapeutic interventions were conversely necessary for acute illnesses that could not be foreseen during the routine physician-patient encounter. Of the many laboratory tests, only the determination of complete blood cell count, serum electrolytes, and calcium and phosphorus levels were frequently associated with therapeutic decisions. No intervention was directly related with x-ray bone examination. On the whole, a subgroup of 11 "high-risk" patients who required frequent and multiple therapeutic interventions was identified, the remaining 43 needing only rare and minor adjustments. It is concluded that routine physical examinations are probably useless in identifying and treating intercurrent problems of patients with chronic end-stage renal failure and that only very few hematochemical laboratory tests should be regularly performed. On the basis of a benefit/risk and benefit/cost examination, it is suggested that personally tailored follow-up schemes would probably be a more appropriate way of monitoring patients on maintenance hemodialysis.
Diagnostic Tests, Routine↗
Acquired renal cystic disease and renal adenocarcinoma in long-term dialysis patients.
Explore the source record for details and available documents.
Adenocarcinoma↗