Low serum albumin and the increased risk of amikacin nephrotoxicity

AIM

The purpose of the present study was to know the incidence and risk factors associated with amikacin nephrotoxicity in a cohort of patients form a general medial center.

STUDY DESIGN

Prospective follow-up of a cohort of 104 patients treated with intravenous amikacin for at least 36 hours. We assessed serum creatinine every other day and amikacin plasma levels at 48 and 96 hours after treatment was begun. Patients with other risk factors to develop acute renal failure were excluded. The study was conducted at the Hospital de Especialidades, Centro Médico de Occidente, Instituto Mexicano del Seguro Social.

RESULTS

Ten patients developed nephrotoxicity (9.6%). According to the logistic regression model, the most powerful predictor of high nephrotoxicity probability was the serum albumin concentration. The lower the serum albumin concentration, the higher the risk of toxicity. The mean serum albumin in the group of patients with nephrotoxicity was 2.6 +/- 0.55 g/dL, while in the group of patients without toxicity it was 3.5 +/- 0.55 g/dL. No differences were observed in the age, sex, diagnosis, renal function and amikacin doses between both groups. Furthermore, low serum albumin concentration was also associated with amikacin accumulation in plasma. The group of patients with hypoalbuminemia (< or = 3.0 g/dL) had a significantly higher trough amikacin plasma level (assessed at 48 and 96 hours of the initiation of treatment) than those with normal serum albumin, with no differences among the age, sex, baseline renal function and received amikacin doses.

CONCLUSIONS

We conclude that serum albumin concentration is the most powerful predictor of amikacin nephrotoxicity. The risk factors observed in the present study are similar to those previously observed by us at the Instituto Nacional de la Nutrición Salvador Zubirán.

Cloning and characterization of an extracellular Ca(2+)-sensing receptor from bovine parathyroid

Maintenance of a stable internal environment within complex organisms requires specialized cells that sense changes in the extracellular concentration of specific ions (such as Ca2+). Although the molecular nature of such ion sensors is unknown, parathyroid cells possess a cell surface Ca(2+)-sensing mechanism that also recognizes trivalent and polyvalent cations (such as neomycin) and couples by changes in phosphoinositide turnover and cytosolic Ca2+ to regulation of parathyroid hormone secretion. The latter restores normocalcaemia by acting on kidney and bone. We now report the cloning of complementary DNA encoding an extracellular Ca(2+)-sensing receptor from bovine parathyroid with pharmacological and functional properties nearly identical to those of the native receptor. The novel approximately 120K receptor shares limited similarity with the metabotropic glutamate receptors and features a large extracellular domain, containing clusters of acidic amino-acid residues possibly involved in calcium binding, coupled to a seven-membrane-spanning domain like those in the G-protein-coupled receptor superfamily.

Primary structure and functional expression of a cDNA encoding the thiazide-sensitive, electroneutral sodium-chloride cotransporter

Electroneutral Na+:Cl- cotransport systems are involved in a number of important physiological processes including salt absorption and secretion by epithelia and cell volume regulation. One group of Na+:Cl- cotransporters is specifically inhibited by the benzothiadiazine (thiazide) class of diuretic agents and can be distinguished from Na+:K+:2Cl- cotransporters based on a lack of K+ requirement and insensitivity to sulfamoylbenzoic acid diruetics like bumetanide. We report here the isolation of a cDNA encoding a thiazide-sensitive, electroneutral sodium-chloride cotransporter from the winter flounder urinary bladder using an expression cloning strategy. The pharmacological and kinetic characteristics of the cloned cotransporter are consistent with the properties of native thiazide-sensitive sodium-chloride cotransporters in teleost urinary bladder and mammalian renal distal tubule epithelia. The nucleotide sequence predicts a protein of 1023 amino acids (112 kDa) with 12 putative membrane-spanning regions, which is not related to other previously cloned sodium or chloride transporters. Northern hybridization shows two different gene products: a 3.7-kb mRNA localized only to the urinary bladder and a 3.0-kb mRNA present in several non-bladder/kidney tissues.

[The aneurysmal degeneration of aortocoronary bypasses. A case report]

A 67-year-old man presenting with oppressive atypical chest pain 13 years after aorto-coronary saphenous vein bypass surgery, was found to have a large left anterior mediastinal mass on chest x-rays. Computerized tomography and digital subtraction angiography showed conflicting evidence on the vascular nature of the structure: the suspect diagnosis was of aortic pseudoaneurysm originating in the area of previous aortic cannulation. Selective coronary and bypass angiography showed extreme irregularity and dilatation of the grafts, and revealed the mediastinal mass to be represented by aneurysmal dilatation of the saphenous vein graft to the obtuse marginal coronary artery, partially filled with thrombus. At operation, another smaller aneurysm was found on the right coronary artery graft. Aneurysmal degeneration of vein grafts in the coronary circulation is exceedingly rare, and in only 6 reported cases has such an aneurysm presented as a mediastinal mass. To our knowledge, this is the first case in which an aneurysmal dilatation involved two saphenous vein coronary grafts.

Evidence of a hypercoagulable state in patients with acute lymphoblastic leukemia treated with low dose of E. coli L-asparaginase: a GIMEMA study

Blood coagulation abnormalities induced by administration of E. coli L-asparaginase were investigated in 25 patients with acute lymphoblastic leukemia treated according to the GIMEMA ALL 0288 trial. Dosage of L-asparaginase was relatively low (6,000 U/m2/day for 7 days total dose 42,000 U/m2) as compared to the conventional dosages (120,000-140,000 U/m2 over 10-14 days). A significant decrease in fibronogen, plasminogen, alpha2-antiplasmin and antithrombin III was observed from day IV of L-asparaginase and it was maximum on day VIII, with return to the baseline levels on day XV. Protein C levels had only a borderline reduction, while no modification of protein S or factor VII was observed. Two of the patients investigated developed thrombosis. The presence of a prothrombotic state induced even by this low dosage of E. coli L-asparaginase was suggested by a significant increase of sensitive markers of hypercoagulability such as fibrinopeptide A, thrombin-antithrombin complexes, and prothrombin fragment F1 + 2.

Death risk in CAPD patients. The predictive value of the initial clinical and laboratory variables

The characteristics, survival rate and risk factors associated with death in patients with end-stage renal failure treated with chronic ambulatory peritoneal dialysis (CAPD) were studied. This is a retrospective study of a cohort of 206 patients, from which the follow-up was complete in 190 patients (92%). Only 16 patients (8%) were lost. The study group is composed of 118 males and 88 females, with a mean age of 39 +/- 15 years. The origin of the renal disease was: unknown in 90 patients (44%); diabetes mellitus in 50 (24%); systemic lupus erythematosus in 16 (8%); obstructive uropathy in 15 (7%); glomerulonephritis in 14 (7%), and miscellaneous in 21 (10%). The average follow-up was 12 +/- 11 months. At the end of study, 66 patients were dead (32%). CAPD was discontinued in 12 (6%). Thirty-eight patients (18%) received kidney transplantation. The survival rate for the whole group was 67 and 48% at 1 and 3 years, respectively. Multivariate survival analysis according to the Cox proportional-hazard model showed that the most powerful predictor associated with high risk of death was low serum albumin levels. According to the Cox model other independent variables significantly associated with increase in the probability of death while on CAPD were advancing age, low serum creatinine concentrations and elevated serum cholesterol levels. These results indicate that the risk factors associated with death in CAPD patients are similar to those observed for hemodialysis patients and suggest that using simple laboratory measurements at the enrollment in CAPD the relative risk of death for each patient can be estimated.

Role of angiotensin II in the antinatriuresis that follows acute volume depletion

The aim of this study was to examine the contribution of the renin angiotensin system to the antinatriuresis that follows acute volume depletion. Four groups of six dogs each were studied. The first group was exposed to saline expansion (8% body weight) (SE). The second group was exposed to acute volume depletion (2% body weight) followed in one hour by saline expansion (AVD). The third and fourth groups were similar but in dogs treated with high doses of captopril (SE + C and AVD + C). Dogs were anesthetized with phenobarbital. Control measurements were made for 30 minutes before and 60 minutes during saline expansion. Glomerular filtration rate (inulin), renal blood flow (para-aminohippuric acid) and mean arterial pressure were similar in the four groups during the experiment. The increase in fractional sodium excretion from the control period to the end of saline expansion was in the SE group from 0.6 +/- 0.2 to 6.4 +/- 1% and in the SE + C group from 1.1 +/- 0.3 to 8.5 +/- 1.3%. In contrast, in the AVD group it only rose from 0.8 +/- 0.2 to 3.5 +/- 0.7% and in the AVD + C group from 1.3 +/- 0.4 to 4.1 +/- 0.6%. Therefore, the increment in sodium excretion during saline expansion was significantly lower in dogs exposed to acute volume depletion, independent of the treatment with captopril. The blunted natriuresis cannot be explained by differences in GFR, RBF or MAP. These results suggest that renin angiotensin system is not the responsible agent of the sodium retention that follows acute volume depletion.

Platelet function after in vivo and in vitro treatment with thrombolytic agents

Whereas in vitro studies showed that plasmin may induce both inhibition and activation of platelets, in vivo and ex vivo investigations suggested that thrombolytic agents are responsible for platelet stimulation. To gain further information on this topic, ex vivo platelet function was studied in 24 subjects with acute myocardial infarction treated with streptokinase or recombinant tissue-type plasminogen activator (rt-PA). Ten patients with acute myocardial infarction who did not receive thrombolytic treatment were also investigated. The data shows that at the end of thrombolytic infusion, the maximal extent of platelet aggregation and adenosine triphosphate release was reduced in treated patients compared with that in untreated ones. In subjects treated with streptokinase, the defect in platelet aggregation derived from both cellular and plasmatic defects. Plasmatic beta-thromboglobulin concentration was significantly reduced after streptokinase, but unchanged after rt-PA. Three days after thrombolytic treatment, platelet aggregation of patients receiving streptokinase or rt-PA was not significantly different from that of untreated subjects. A similar defect in platelet function was obtained in vitro, incubating normal platelet-rich plasma with pharmacologic concentrations of streptokinase. Again, platelet function defect derived from both cellular and plasmatic damages. It cannot be excluded that platelet activation occurs in patients with acute myocardial infarction during the very early phases of thrombolytic treatment. However, it is suggested that a transient defect in platelet function follows both streptokinase and rt-PA infusion.

Clotting abnormalities in children during maintenance chemotherapy for acute lymphoblastic leukemia

BACKGROUND

Many of the drugs used in the treatment of acute lymphoblastic leukemia in children may induce modifications in different organs and functions. Following the observation of a recurrent, mild delay in the prothrombin time in ALL children during maintenance chemotherapy, we explored the main parameters of the clotting function.

METHODS

17 children with acute lymphoblastic leukemia were studied during maintenance chemotherapy for clotting function screening evaluation; 15 healthy children, matched for age and sex, were used as controls.

RESULTS

A uniform pattern of slight prolongation of the prothrombin time with significantly reduced levels of factors VII, IX, and a trend toward reduced activity of factor X was observed in the absence of any demonstrable anticoagulant factor.

CONCLUSIONS

Antileukemic maintenance chemotherapy is associated with a subclinical modification of the clotting parameters that is not responsible for hemorrhagic diathesis. Long-term administration of anti-metabolites (6-mercaptopurine and methotrexate) could be responsible for this reversible impairment.

Purpura fulminans as clinical manifestation of atypical SLE with antiphospholipid antibodies: a case report

Purpura Fulminans and DIC were the main clinical manifestations of the antiphospholipid syndrome observed in a 62-year-old man. The patient was well until 44 years of age when he began to suffer from recurrent thrombophlebitis, without other symptoms suggestive of immune disease. At the time of hospital admission the pt. appeared acutely ill, showing high fever, severe anemia, massive urinary blood loss, multiple purpuric patches evolving to hemorrhagic bullae and gangrene rapidly spreading over about 30% of the total body area. No signs of neurological involvement or of visceral thrombotic occlusions were present. Clotting tests were consistent with a diagnosis of DIC, further confirmed by skin biopsy showing the presence of thrombi in dermal arterioles. The autoantibody research was positive as follows: Waaler-Rose 1:40, Anti-DNA 1:80; ANF 1:640, aCA IgG 100 GPL. LA was diagnosed according to standard criteria: prolonged KCT and RVVT not corrected by a mixture of normal plasma and abnormal TTI. Plasma exchange in association with heparin and prednisone was effective in arresting the progression of the skin lesion; nevertheless the patient died ten days after hospital admission for sepsi and acute renal failure.

Bicarbonate therapy in severe diabetic ketoacidosis. A double blind, randomized, placebo controlled trial

Intravenous sodium bicarbonate has been used for a long time in the treatment of diabetic ketoacidosis. However, there are no clinical studies showing its effectiveness in improving arterial pH in this condition. We therefore designed this study to investigate if bicarbonate therapy improves the rate of increase of arterial pH and to find out its effects on the recovery rate of the other metabolic abnormalities. Twenty patients with severe diabetic ketoacidosis (pH less than 7.15) entered a double-blind, randomized, placebo controlled trial: nine were included in the bicarbonate group and eleven in the placebo group. All patients were studied during the first 24 hours of treatment. Their management was similar, except for the use of sodium bicarbonate in one group and 0.9% saline solution in the placebo group. Heart rate, respiratory rate, arterial pressure, mental status, blood gases, blood glucose, sodium, potassium, and urea were assessed at the beginning of treatment, and then at 2, 6, 12 and 24 hours. No clinical or metabolic differences were found between groups. Two hours after therapy was begun, the arterial pH rose in the bicarbonate group from 7.05 +/- 0.08 to 7.24 +/- 0.04, while it only rose from 7.04 +/- 0.08 to 7.11 +/- 0.09 in the placebo group (p less than 0.02). Simultaneously, arterial bicarbonate increased from 2.87 +/- 1.2 to 6.1 +/- 1.5 mEq/L in the bicarbonate group and from 2.55 +/- 0.81 to 3.6 +/- 2 mEq/L in the placebo group (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Observer agreement in the scoring of the activity and chronicity indexes of lupus nephritis

The present study was designed to evaluate the observer reliability in the scoring of the activity and chronicity indexes, among three experienced pathologists, in renal biopsies from lupus nephritis (LN). Twenty-five renal biopsies of LN, were evaluated independently by three pathologists to assess the interobserver variability. For the intraobserver agreement, 5 biopsies were evaluated twice by each pathologist. The interobserver agreement for the scoring of the activity and chronicity indexes was 0.81 and 0.86, respectively. In the intraobserver agreement the same results were: for the pathologist 1, 0.95 and 0.70; for the pathologist 2, 0.91 and 0.55; for the pathologist 3, 0.89 and 0.82. In conclusion the agreement for the scoring of the activity and chronicity indexes in biopsies from LN was excellent.

Hypoalbuminemia as a risk factor for amikacin nephrotoxicity

Hypoalbuminemia has been recently informed by us as a risk factor in aminoglycoside nephrotoxicity. Since amikacin has a low serum binding capacity to albumin, the present study was designed to determine if the higher risk of amikacin nephrotoxicity in patients with hypoalbuminemia was due to low serum albumin per se or to malnutrition. One-hundred and thirteen ward patients who received endovenous amikacin for greater than 36 hours were studied prospectively. All were evaluated for the following factors: age, sex, diagnosis, serum creatinine, serum albumin, and nutritional status. They were followed with serum creatinine twice a week until cessation of therapy. Amikacin pharmacokinetics was studied in 11 subjects: 6 patients had a serum albumin less than 3.0 g/dL and 5 greater than 3.0 g/dL, but there were no differences in age, sex, weight, diagnosis, arterial pressure and nutritional status. The overall incidence of toxicity was 11%. In patients with serum albumin less than 3.0 g/dL it was 17.3% and in those greater than 3.0 g/dL it was 2.2%, p less than 0.05. There was no difference in the nutritional status between toxicity and non-toxicity groups. In the pharmacokinetic study, the peak levels obtained one hour after amikacin administration were higher in patients with serum albumin less than 3.0 g/dL than in those with normal serum albumin (12.7 +/- 1.6 vs 9.0 +/- 1.2, p less than 0.002). In conclusion hypoalbuminemia is a risk factor in aminoglycoside nephrotoxicity regardless of the nutritional status.

Amikacin nephrotoxicity in patients with chronic liver disease

Chronic liver disease is a risk factor for aminoglycoside nephrotoxicity. We conducted this study to identify the incidence and risk factors associated with it. A total of 45 patients with liver disease and 329 controls were included, with a toxicity incidence of 17.7%, similar to that in controls. Chronic liver disease patients received lower amikacin doses than calculated on the basis of creatinine clearance (498 +/- 1187 vs 611 = 313 mg/day). Serum albumin, both at the beginning of the treatment and at the end was lower in patients who developed toxicity, and bilirubin levels were higher in these patients at the end of the treatment. Apparently, a dose reduction may lessen the risk for amikacin nephrotoxicity in patients with chronic liver disease. We conclude that hypoalbuminemia and hyperbilirubinemia are risk factors in this complication.

[Membranous glomerulonephritis. Experience at the Instituto Nacional de la Nutrición Salvador Zubirán]

The purpose of this retrospective study was to study the incidence of idiopathic and secondary forms of membranous nephropathy in our institution, its clinical course and progression to chronic renal failure, and the risk factors associated with it. Two hundred fourteen (16%) of the 1,287 renal biopsies obtained between 1962 and 1988 were primary glomerular diseases and 28 of this 214 (13%) were idiopathic membranous nephropathy. On the other hand 59 of 1,287 biopsies were membranous nephropathy of whom 28 were idiopathic, 27 secondary to systemic lupus erythematosus, 2 due to drugs, one associated with rheumatoid arthritis, and one more with breast cancer. The clinical picture was: nephrotic syndrome in 84%, hypertension in 15%, non-nephrotic proteinuria in 14%, chronic renal failure in 8.4%, and renal vein thrombosis in 6.3%. In the idiopathic group 75% of the patients were male while in the lupus group 85% were female. For the analysis of progression to chronic renal failure we excluded 5 patients with renal failure when the biopsy was taken, 2 because the nephropathy was due to drugs, one associated with breast cancer, and nine were within the first year of follow-up. Thus, for this analysis the group consisted of 22 patients with idiopathic form and 20 with systemic lupus erythematosus. The idiopathic and lupus groups were similar except for a lower serum albumin in the former. The progression to renal failure was seen in 9 patients: six in the idiopathic group and the other 3 in the lupus group; this difference was not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Study of three patients with monoclonal gammopathies and 'lupus-like' anticoagulants

In three patients with monoclonal gammopathies: a case of multiple myeloma, a case of monoclonal gammopathy of uncertain significance (MGUS) and a case of monoclonal gammopathy associated with lymphocytic lymphoma, we found the presence of a circulating lupus-like anticoagulant. Coagulative studies showed that the paraproteins: an IgG3k, an IgG1k and an IgMlambda, were responsible for the anticoagulant activity by interacting with the thromboplastin phospholipids. Using isoelectrofocusing we demonstrated that the three monoclonal immunoglobulins had a strong basic charge which may have contributed to determining their interaction with the acidic thromboplastin phospholipids. The binding of various phospholipids to the monoclonal proteins was assessed by the fluorescence quenching method which showed heterogeneous specificity. In order to establish whether the electrical charge is also relevant in cases with polyclonal lupus anticoagulant, the polyclonal immunoglobulins were fractionated according to their charge. The strongest inhibitor activity was found in the most basic immunoglobulins. Monoclonal lupus-like anticoagulants represent useful tools for investigating the heterogeneous world of polyclonal lupus-like anticoagulants.

Serial trough and peak amikacin levels in plasma as predictors of nephrotoxicity

We studied 113 patients treated with intravenous amikacin to determine the value of determining serial trough and peak amikacin levels in plasma for predicting nephrotoxicity. Thirteen patients (11.5%) developed renal toxicity, with significant increases from 48 to 96 h in both peak and trough amikacin levels (6.7 +/- 4.7 [standard deviation] days before the serum creatinine rose). The nontoxicity group had no change or even showed decrements in amikacin levels in plasma. A higher nephrotoxicity risk was seen in patients with increments greater than 1 microgram/ml between 48 and 96 h, with odds ratios of 16.4 for trough, 8 for peak, and 7.2 for both levels. We suggest that an increment of at least 1 microgram/ml in amikacin levels in plasma from 48 to 96 h may predict the appearance of renal toxicity.

[The safe transportation of children in automobiles]

The Author emphasizes the significant number of children who sustain fatal accidents during their transport on motor vehicles and relates the Act recently promulgated by the Italian Parliament on the mandatory use of particular restraining devices as well as safety harness for children.