The humoral response to Puumala virus infection (nephropathia epidemica) investigated by viral protein specific immunoassays

Enzyme-linked immunosorbent assays for determination of antibodies directed to the nucleocapsid protein (N) or to either of the two envelope glycoproteins (G1 and G2) of Puumala virus were designed and evaluated. The assays were proven to be entirely restricted for each viral structural protein by biotin-labelled monoclonal antibodies. Sera from sequentially bled nephropathia epidemica patients (acute, convalescent, and 2-year sera) and sera from 10-20 year convalescents were examined for antibody specificity. All but one (n = 19) acute phase sera were shown to contain IgM antibodies directed to all three viral proteins. In the convalescent specimens the proportions of IgM to the different viral components were similar, but lower, when compared to the acute samples. Low levels of IgM against N and G2 were found in two out of ten 2-year sera. No virus-specific IgM were detected in sera drawn 10-20 years after infection. IgG antibodies to all three viral proteins were detected in all except one acute phase serum. The IgG response initially increased more rapidly to N, as compared to the anti-glycoprotein responses. The levels of glycoprotein-specific IgG were considerably increased 2 years after the disease, when compared to the levels detected in the convalescent specimens. The levels and specificities of IgG in very late convalescent sera (drawn 10-20 years after disease) resembled those detected 2 years after infection.

Pentamidine-induced dysglycaemia: experimental models in the rat

In order to analyse further the pathophysiology of pentamidine effects on blood glucose regulation, the following experimental models were established in rats: impairment of the renal function, bile duct ligation, inhibition of the P450 cytochrome enzyme system. In otherwise intact rats, 7.5 mg/day pentamidine was well tolerated whereas doses of 15 mg/day induced severe, relapsing and eventually lethal hypoglycaemia within a few days. Induction of a renal insufficiency of graded severity by treatment with gentamycin, subtotal nephrectomy and total bilateral nephrectomy resulted in repetitive, severe (sometimes lethal) hypoglycaemia, alternating with hyperglycaemia, glucosuria and ketonuria in pentamidine-treated rats (7.5 mg/d). No long-standing insulin-dependent diabetes was observed. In the dysglycemic animals, plasma insulin levels were inappropriate to the concomitant glycaemia; no stimulation was obtained by i.v. glucose. Glucagon levels were higher than normal, suppressible by i.v. glucose, responsive to IV arginine and to hypoglycaemia. Dysglycemic events were more frequent and marked in the rats with the most severe renal functional derangement. They were more frequent in the rats treated with pentamidine mesylate than in those treated with the isethionate salt. Control uremic rats (free of pentamidine) remained euglycaemic. The islets of Langerhans displayed severe vascular congestion and degranulation and necrosis of the B cells, while the non B cells (and particularly the A cells) were intact. Exocrine pancreatitis was occasionally observed in the most severely uremic rats. In contrast with uremic rats, neither surgical ligation of choledocus, nor treatment by P450 cytochrome inhibitors (particularly ketoconazole) precipitated dysglycaemia in the pentamidine-treated rats. These experimental data: 1) strengthen the concept of inappropriate insulin release from pentamidine-lesioned islet B cells due to pentamidine accumulation; 2) indicate a predominant role for renal insufficiency in determining the accumulation of this drug; 3) emphasize the clinical importance of renal insufficiency as a risk factor for pentamidine-induced dysglycaemia. Association with ketoconazole does not appear to be a risk factor.

Short-term course of renal function in accelerated hypertension

Thirty-four patients with primary accelerated hypertension were studied regarding the effect of BP on renal function and the association between fundal grade and renal function before treatment; and the changes in renal function on normalization of BP in 12 patients. Mean arterial pressure was negatively correlated with serum creatinine (r = -0.44, P < 0.02) and there was no significant difference in serum creatinine or in the occurrence of renal failure between patients with grade III (n = 21) and grade IV (n = 13) retinopathy, (P = n.s. and X2 = 0.172 P = n.s. respectively). Twenty-two patients required dialysis at presentation. Serum creatinine rose in 12 other patients on reduction of BP; 7 patients with serum creatinine level < or = 3.2 mg/dL (283 umol/L) at presentation never required dialysis in the 3 months following reduction of BP while those with levels > or = 3.6 mg/dL (319 umol/L) did. In accelerated hypertension, renal function is partly maintained by the blood pressure and dialysis may be required soon after presentation or normalization of BP.

Magnetic resonance angiography and detection of renal artery stenosis in a patient with impaired renal function

Diagnosing renovascular disease in patients with renal insufficiency has challenged physicians for many years. Although contrast angiography is the "gold standard," it is associated with major risks in patients with preexisting renal failure. Other noninvasive tests have not proved to have sufficient sensitivity and specificity to supplant angiography. Developments in magnetic resonance (MR) angiographic technology, however, now enable physicians to assess the vasculature noninvasively and without use of potentially nephrotoxic agents. Herein we describe a patient with hypertension and renal failure in whom MR angiography proved to be the only effective noninvasive test for diagnosing renal artery stenosis. In addition, we review the current literature on MR angiography for renovascular disease. In the setting of renal impairment, MR angiography may be useful in screening patients for renovascular disease. More studies are needed in order to refine MR angiographic techniques and, ultimately, to determine specific situations in which MR angiography may be useful.

A prospective study of blood pressure and serum creatinine. Results from the 'Clue' Study and the ARIC Study

OBJECTIVES

To describe associations of past and current blood pressure levels with serum creatinine levels and hypercreatinemia in the general population.

POPULATION

1399 middle-aged residents of Washington County, Maryland, who had their blood pressure measured during a cancer screening campaign in 1974 (the "Clue" Study) and had their blood pressure and serum creatinine level measured in an atherosclerosis risk factors study from 1986 through 1989 (the Atherosclerosis Risk in Communities [ARIC] Study).

DESIGN

Nonconcurrent prospective study. The outcome variables were serum creatinine level and hypercreatinemia (serum creatinine > 115 mumol/L in men, > 97 mumol/L in women) measured from 1986 through 1989. Main predictors were 1986-1989 blood pressure values (cross-sectional association) and 1974 blood pressure values (longitudinal association). Gender-adjusted associations were assessed and compared by linear and logistic regression.

RESULTS

Both serum creatinine and hypercreatinemia were better predicted by past than by current blood pressure values. Creatinine values exhibited a gradual and statistically significant association with blood pressure levels measured in 1974, even across "normal" values of blood pressure and creatinine. The association with 1986-1989 blood pressure measurements was weaker and nonsignificant. The odds of hypercreatinemia in 1986-1989 were increased 1.5-fold to twofold, with a 20 mm Hg increment in 1974 blood pressure values, but the odds remained constant across 1986-1989 blood pressure values.

CONCLUSIONS

Blood pressure and creatinine level are associated in the general population. The observed association was stronger when a number of years had elapsed between the assessments of blood pressure and creatinine level. These findings are consistent with the hypothesis that blood pressure elevations, even below the hypertensive range, may induce early renal damage.

[Rate of in vitro degradation of vecuronium in plasma of patients with renal failure and pregnancy]

The half-life of vecuronium in plasma by spontaneous desacetylation is about 120 minutes. We have to consider this degradation for examining the cause of prolonged duration of action of vecuronium. Therefore the rate of in vitro plasma spontaneous desacetylation of vecuronium bromide was measured in healthy women (n = 10), patients with renal failure (n = 10) and pregnant women (n = 10). There were no significant differences between three groups. It was concluded that the rate of spontaneous desacetylation was not responsible for the cause of prolonged neuromuscular blockade of vecuronium in patients with renal failure and pregnancy.

Mesangial cell proliferation is directly enhanced by sera from patients with renal insufficiency

We undertook the present study to determine whether there is a direct effect of sera from patients with renal insufficiency on mesangial cell proliferation. Growth-arrested mesangial cells were incubated with sera from patients with varying degrees of renal insufficiency and then pulsed with [3H]thymidine. Thymidine uptake was progressively greater with more advanced renal failure and was linearly correlated with (creatinine)-1. This data suggests that serum from patients with loss of renal function contains mitogens capable of directly enhancing mesangial cell proliferation.

The influence of renal failure on the kinetics of intravenous midazolam: an "in vitro" and "in vivo" study

The effect of renal failure upon the "in vitro" binding of midazolam, a new water-soluble short-acting benzodiazepine, has been studied in man. An increase of its free fraction (ranging from 2.52 to 5.17%) in serum from uremic patients was observed. A similar situation was originated in rabbits by administering uranyl nitrate (2 mg/Kg i.v.) and posterior hypnosis with midazolam. Uremic rabbits showed a marked increase in the free concentration of midazolam in serum (ranging from 8.9 to 13.7 micrograms/ml) and in midazolam brain levels (156.2 micrograms/g in cortex vs 84.5 micrograms/g in control animals). A positive correlation between brain and serum free concentration of midazolam was also observed. It is concluded that in renal patients more unbound drug is available to produce central nervous system effects, and a decrease in intravenous dose of midazolam could be recommended in this clinical situation.

Two-site assays of bone gla protein (osteocalcin) demonstrate immunochemical heterogeneity of the intact molecule

We developed a panel of monoclonal antibodies to human bone gla protein (BGP; osteocalcin) peptides that span the linear sequence of the molecule, specifically BGP 1-12 (N-terminal), BGP 15-30 (midregion), and BGP 38-49 (C-terminal). These antibodies were evaluated in various combinations of two-site formats in studies of serum BGP concentrations. For clinical studies, we selected from a panel of antibodies the two most sensitive antibody pairs for the intact molecule (N-C); we also used a polyclonal RIA based on BGP-C. For the two-site format, we used two N-terminal antibodies, 029 and 052, adsorbed to polystyrene beads, and radioiodinated a C-terminal antibody, 663. The standard for each of the assays was purified human BGP. The following BGP serum concentrations (microgram/L, mean +/- SE) were measured with the various assays: by the 029-663 assay, results for normal subjects were 7 +/- 3, for patients with renal failure 25 +/- 8, and for patients with Paget disease 12 +/-4; by the 052-663 assay, the respective results were 22 +/- 4, 44 +/- 12, and 31 +/- 7; by the polyclonal assay, the results were 3 +/- 0.2, 13 +/- 2, and 5 +/- 1. The two intact (N-C) assays were significantly (P < 0.01) correlated (r = 0.94), but their serum values differed by more than twofold in terms of the same BGP standard. The polyclonal assay significantly correlated with each of the intact assays (r = 0.83, 0.77), but it, too, gave different serum values for BGP. These studies demonstrate the immunochemical heterogeneity of circulating BGP, heterogeneity that is manifest even in immunoassays specific for the same region of the molecule.

Sandwich immunoassay for intact human osteocalcin

To overcome the problems of limited-region specificity associated with conventional radioimmunoassay (RIA), we developed a sandwich enzyme immunoassay (EIA) for intact human osteocalcin (hOC). For this EIA we used antibodies to the N- and C-terminal regions of hOC that were raised against an N-terminal 20-residue peptide and a C-terminal 7-residue peptide, both synthetic. Immunoassay profiles of tryptic digests of hOC and serum from patients with renal failure, fractionated by reversed-phase HPLC, facilitated direct demonstration of the region specificity of this method. A preliminary study of serum osteocalcin concentrations in patients with renal failure further confirmed this specificity, showing lower positive rates obtained by this method than by conventional RIA. The cross-reactivity data of hOC with bovine and rat osteocalcins by the sandwich method indicated its species specificity. These studies demonstrate the superior specificity of this sandwich EIA compared with conventional RIA and thus confirm its potential diagnostic superiority.

Specific and high affinity binding of perindoprilat, but not of perindopril to blood ACE

The bindings of perindopril and of its active metabolite perindoprilat to human serum, isolated proteins and to erythrocytes were studied by equilibrium dialysis. Within the therapeutic concentrations range, perindopril was 74% bound to serum involving a non-saturable process, NKa = 2.87. The main binders are serum albumin and alpha 1-acid glycoprotein. The serum binding of perindoprilat involved two successive steps. First, a saturable high-affinity binding (Ka: 2.8 x 10(9) M-1) occurred, involving probably the angiotensin converting enzyme (ACE). The second binding step was non-saturable with a very weak binding capacity, NKa = 0.15, quite superimposable to the HSA bound perindoprilat. Free fatty acids (FFA) did not alter the binding to HSA. The binding of both compounds to erythrocytes was low especially with perindopril, when measured in the presence of plasma. A significant correlation showed that the overall serum binding percentage of both drugs was essentially determined by HSA concentration. Serum binding was decreased in renal failure or cirrhosis, this result was principally linked to the hypoalbuminemia. Interactions with other drugs were limited to the binding of salicylate, tolbutamide and digitoxin to HSA.

Renal insufficiency induced by parathyroid hormone: influence of the calcium antagonist Gö 6070

To study the pathogenesis of parathyroid-hormone-induced renal insufficiency and the influence of the new calcium channel antagonist Gö 6070 (Gödecke AG, Berlin, FRG) rats were assigned to three groups (n = 8 each): (1) control, (2) PTH, (3) PTH plus Gö 6070. PTH (30 micrograms/24 h, a nonhypercalcemic dose) was administered i.p. and Gö 6070 (1 mg/kg/24 h) p.o. for 6 days. PTH did not change plasma or urinary calcium and did not induce nephrocalcinosis. The glomerular filtration rate (GFR), however, was decreased (4.9 vs. 10.3 ml/min/kg). Concomitant administration of Gö 6070 attenuated the PTH-induced fall in GFR (6.2 ml/min/kg).

[The pathogenesis of the renal syndrome in hemorrhagic fever]

Lipid peroxidation was investigated in 89 patients suffering from hemorrhagic fever with renal syndrome. In addition to routine tests, measurements were made of plasma malonic dialdehyde and acyl hydroperoxides the levels of which were found increased 1.3-1.4-fold and 1.5-2-fold, respectively, in the severe disease compared to control values. The degree of lipid peroxidation intensification and aggravation of the symptoms proved to agree. It is suggested that abnormal lipid peroxidation contributes to development of renal syndrome which in hemorrhagic fever may progress to acute renal failure.

Distribution characteristics of mitoxantrone in a patient undergoing hemodialysis

The pharmacokinetic profile of mitoxantrone in a patient undergoing hemodialysis is described. Significant characteristics of our patient included lymphoma with liver involvement, tumor lysis syndrome, renal and hepatic failure. Combination chemotherapy consisted of mitoxantrone, vincristine, and cyclophosphamide. Mitoxantrone plasma samples were obtained prior to dosing and at 0, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.5, 7.0, and 12 h after the intravenous infusion of a 17-mg dose over 20 min. Serum concentrations were determined by high-performance liquid chromatography. The serum concentration versus time curve was consistent with a three-compartment model. However, rebounds in serum drug concentrations were detected during the last portion of dialysis and after its completion. The gamma elimination half-life could not be determined due to the continued detection of rebounds in drug concentrations throughout the postdialysis sampling period. The alpha and beta distribution phases did not appear to be affected by hemodialysis. The peak mitoxantrone concentration fell within the reported range. Mitoxantrone does not appear to be eliminated by hemodialysis, and dose adjustments are not needed in patients undergoing this procedure.

The studies on the gastrin levels in the patients with renal failure

Fasting and postprandial gastrin levels were measured by radioimmunoassay in serum from 15 patients with renal failure and compared with those in 15 healthy controls. Pre- and posthemodialysis gastrin levels were also measured.

The fasting serum gastrin levels and serum gastrin response to a standard meal in the patients with renal failure were significantly higher than those in normal controls.

Fasting and meal stimulated gastrin levels were not significantly different in renal failure patients with peptic ulcer when compared with those in renal failure patients without peptic ulcer.

There were no statistically significant differences in the serum gastrin levels before and after hemodialysis in patients with renal failure.