Kalemia during combined therapy with an angiotensin converting enzyme inhibitor and a potassium-sparing diuretic.

Both angiotensin converting enzyme (ACE) inhibitors and potassium-sparing diuretics tend to increase serum potassium levels. This retrospective study was undertaken to assess whether these two types of agents can nevertheless be combined safely. Twelve hypertensive patients were treated for 1-70 months (mean = 17) with an ACE inhibitor together with a potassium-sparing diuretic (spironolactone, n = 10; amiloride, n = 2). In addition, eight patients also took a thiazide or a loop diuretic. Nine patients had a normal and three a slightly impaired renal function. No clinically relevant hyperkalemia was observed during the course of the study. These data suggest that it is not impossible to combine an ACE inhibitor with a potassium-sparing diuretic, as long as renal function is normal and serum potassium concentration is monitored closely.

Role of bradykinin in the neonatal renal effects of angiotensin converting enzyme inhibition.

The vascular effects of angiotensin converting enzyme inhibitors are mediated by the inhibition of the dual action of angiotensin converting enzyme (ACE): production of angiotensin II and degradation of bradykinin. The deleterious effect of converting enzyme inhibitors (CEI) on neonatal renal function have been ascribed to the elevated activity of the renin-angiotensin system. In order to clarify the role of bradykinin in the CEI-induced renal dysfunction of the newborn, the effect of perindoprilat was investigated in anesthetized newborn rabbits with intact or inhibited bradykinin B2 receptors. Inulin and PAH clearances were used as indices of GFR and renal plasma flow, respectively. Perindoprilat (20 microg/kg i.v.) caused marked systemic and renal vasodilation, reflected by a fall in blood pressure and renal vascular resistance. GFR decreased, while urine flow rate did not change. Prior inhibition of the B2 receptors by Hoe 140 (300 microg/kg s.c.) did not prevent any of the hemodynamic changes caused by perindoprilat, indicating that bradykinin accumulation does not contribute to the CEI-induced neonatal renal effects. A control group receiving only Hoe 140 revealed that BK maintains postglomerular vasodilation via B2 receptors in basal conditions. Thus, the absence of functional B2 receptors in the newborn was not responsible for the failure of Hoe 140 to prevent the perindoprilat-induced changes. Species- and/or age-related differences in the kinin-metabolism could explain these results, suggesting that in the newborn rabbit other kininases than ACE are mainly responsible for the degradation of bradykinin.

Genetic structure of the genus Leptospira by multilocus enzyme electrophoresis

Thirty strains from the 11 species of the genus Leptospira were studied by multilocus enzyme electrophoresis at 12 enzyme loci, all of which were polymorphic. The mean number of alleles per locus was 6.5. Twenty-five electrophoretic types were distinguished. Grouping of the strains by cluster analysis was in general agreement with species delineation as determined by DNA-DNA hybridization, except for the strains of Leptospira meyeri and Leptospira inadai, which were scattered throughout the genus, reflecting previously recognized taxonomic uncertainties. Analysis of the clonality within Leptospira interrogans sensu stricto indicated that this population was relatively heterogeneous and a lack of gene linkage disequilibrium could not be excluded. There was a genetic discrimination between the pathogenic species and the saprophytic ones. The phenotypically intermediate species (L. inadai and Leptospira fainei) were also genetically separated and were probably closer to the saprophytes than to the pathogens.

Clinical results of enzyme replacement therapy in Fabry disease: a comprehensive review of literature.

Enzyme replacement therapy (ERT) has been used to treat Fabry disease - a progressive lysosomal storage disorder - since 2001. Two preparations of the enzyme alpha-galactosidase A are available in Europe: agalsidase alpha, produced in a human cell line, and agalsidase beta, produced in Chinese hamster ovary cells. To review critically the published evidence for the clinical efficacy of these two enzyme preparations. A systematic literature search was undertaken to identify open or randomised controlled trials published on Fabry disease since 2001. Eleven trials fulfilled the criteria for inclusion in this review, of a total of 586 references on Fabry disease. To date, no direct comparisons exists between the two available enzyme preparations. Significant clinical benefits compared with placebo, however, have been demonstrated with ERT, with positive effects on the heart, kidneys, nervous system and quality of life. The quality of most of these publications was less than optimal. Further prospective studies are required to confirm the long-term clinical benefits of ERT. More studies are also needed on the effects of ERT in women and on the use of ERT early in the course of Fabry disease, to prevent organ damage. Large national and international outcomes databases will also be invaluable in evaluating treatment effects and safety.

Dual role of the antioxidant enzyme peroxiredoxin 6 in skin carcinogenesis.

The antioxidant enzyme peroxiredoxin 6 (Prdx6) is a key regulator of the cellular redox balance, particularly under stress conditions. We identified Prdx6 as an important player in different phases of skin carcinogenesis. Loss of Prdx6 in mice enhanced the susceptibility to skin tumorigenesis, whereas overexpression of Prdx6 in keratinocytes of transgenic mice had the opposite effect. The tumor-preventive effect of Prdx6, which was observed in a human papilloma virus 8-induced and a chemically induced tumor model, was not due to alterations in keratinocyte proliferation, apoptosis, or in the inflammatory response. Rather, endogenous and overexpressed Prdx6 reduced oxidative stress as reflected by the lower levels of oxidized phospholipids in the protumorigenic skin of Prdx6 transgenic mice and the higher levels in Prdx6-knockout mice than in control animals. In contrast to its beneficial effect in tumor prevention, overexpression of Prdx6 led to an acceleration of malignant progression of existing tumors, revealing a dual function of this enzyme in the pathogenesis of skin cancer. Finally, we found strong expression of PRDX6 in keratinocytes of normal human skin and in the tumor cells of squamous cell carcinomas, indicating a role of Prdx6 in human skin carcinogenesis. Taken together, our data point to the potential usefulness of Prdx6 activators or inhibitors for controlling different stages of skin carcinogenesis.

Monoclonal antibodies against carcinoembryonic antigen (CEA) used in a solid-phase enzyme immunoassay. First clinical results.

A solid-phase enzyme immunoassay using both mouse monoclonal and goat polyclonal antibodies against carcinoembryonic antigen (CEA) was developed. The assay detects 0.6 to 1.2 ng of CEA per ml of serum and has 3 incubation steps which can be performed in 1 day. Polystyrene balls coated with polyclonal goat anti-CEA antibodies are first incubated with heat-extracted serum samples. Bound CEA is then detected by addition of mouse monoclonal antibodies, followed by goat IgG anti-mouse IgG1 coupled to alkaline phosphatase. Results with this enzyme immunoassay using monoclonal antibodies (M-EIA) have been compared with those obtained by the conventional inhibition radioimmunoassay (RIA) using goat antiserum. Three hundred and eighty serum samples from 167 patients with malignant or non-malignant diseases and from 134 normal individuals with or without heavy smoking habits were analyzed by the 2 assays. Excellent correlation between the results of the 2 assays was obtained, but the M-EIA, using monoclonal antibodies from a single hybridoma, did not discriminate better than the conventional RIA between CEA produced by different types of carcinoma and between CEA associated with malignant or non-malignant diseases. Follow-up studies of several patients by sequential CEA determinations with the 2 assays showed that the M-EIA was as accurate as the RIA for the detection of tumor recurrences.

Assignment strategies for large proteins by magic-angle spinning NMR: the 21-kDa disulfide-bond-forming enzyme DsbA.

We present strategies for chemical shift assignments of large proteins by magic-angle spinning solid-state NMR, using the 21-kDa disulfide-bond-forming enzyme DsbA as prototype. Previous studies have demonstrated that complete de novo assignments are possible for proteins up to approximately 17 kDa, and partial assignments have been performed for several larger proteins. Here we show that combinations of isotopic labeling strategies, high field correlation spectroscopy, and three-dimensional (3D) and four-dimensional (4D) backbone correlation experiments yield highly confident assignments for more than 90% of backbone resonances in DsbA. Samples were prepared as nanocrystalline precipitates by a dialysis procedure, resulting in heterogeneous linewidths below 0.2 ppm. Thus, high magnetic fields, selective decoupling pulse sequences, and sparse isotopic labeling all improved spectral resolution. Assignments by amino acid type were facilitated by particular combinations of pulse sequences and isotopic labeling; for example, transferred echo double resonance experiments enhanced sensitivity for Pro and Gly residues; [2-(13)C]glycerol labeling clarified Val, Ile, and Leu assignments; in-phase anti-phase correlation spectra enabled interpretation of otherwise crowded Glx/Asx side-chain regions; and 3D NCACX experiments on [2-(13)C]glycerol samples provided unique sets of aromatic (Phe, Tyr, and Trp) correlations. Together with high-sensitivity CANCOCA 4D experiments and CANCOCX 3D experiments, unambiguous backbone walks could be performed throughout the majority of the sequence. At 189 residues, DsbA represents the largest monomeric unit for which essentially complete solid-state NMR assignments have so far been achieved. These results will facilitate studies of nanocrystalline DsbA structure and dynamics and will enable analysis of its 41-kDa covalent complex with the membrane protein DsbB, for which we demonstrate a high-resolution two-dimensional (13)C-(13)C spectrum.

Perampanel: a significant liver enzyme inducer in some patients?

Perampanel is one of the latest released antiepileptic drugs (AEDs). Early studies suggest no significant liver enzyme induction from this compound. We report on two patients with medically resistant epilepsy, who had perampanel added to their usual regimen. Both experienced a worsening of their epilepsy and presented in convulsive status epilepticus; concurrent antiepileptic drug levels (phenytoin, phenobarbital, rufinamide) were significantly decreased (<50%) in comparison with levels prior to perampanel introduction. Intravenous load and significant increase of maintenance dosages were needed to restore therapeutic drug levels. In one patient, further increase of perampanel resulted in a new drop of phenytoin level. This suggests that perampanel could, in some subjects, induce liver enzymes and interact with concomitant AEDs; monitoring levels of concomitant compounds could be useful.

Liver enzyme elevation after lamivudine withdrawal in HIV-hepatitis B virus co-infected patients: the Swiss HIV Cohort Study.

Background The principal causes of liver enzyme elevation among HIV-hepatitis B virus (HBV) co-infected patients are the hepatotoxic effects of antiretroviral therapy (ART), alcohol abuse, ART-induced immune reconstitution and the exacerbation of chronic HBV infection. Objectives To investigate the incidence and severity of liver enzyme elevation, liver failure and death following lamivudine (3TC) withdrawal in HIV-HBV co-infected patients. Methods Retrospective analysis of the Swiss HIV Cohort Study database to assess the clinical and biological consequences of the discontinuation of 3TC. Variables considered for analysis included liver enzyme, HIV virological and immunological parameters, and medication prescribed during a 6-month period following 3TC withdrawal. Results 3TC was discontinued in 255 patients on 363 occasions. On 147 occasions (109 patients), a follow-up visit within 6 months following 3TC withdrawal was recorded. Among these patients, liver enzyme elevation occurred on 42 occasions (29%), three of them (2%) with severity grade III and five of them (3.4%) with severity grade IV elevations (as defined by the AIDS Clinical Trials Group). Three patients presented with fulminant hepatitis. One death (0.7%) was recorded. Conclusions HBV reactivation leading to liver dysfunction may be an under-reported consequence of 3TC withdrawal in HIV-HBV co-infected patients. Regular monitoring of HBV markers is warranted if active therapy against HBV is discontinued.

Effect on blood pressure and the renin-angiotensin system of repeated doses of the converting enzyme inhibitor CGS 14824A.

A new, orally active angiotensin converting enzyme (ACE) inhibitor, CGS 14824A, was evaluated in 12 healthy male volunteers. Two groups each of 6 volunteers were given 5 or 10 mg once daily p.o. for 8 days. Four hours after the first and the last morning doses, plasma angiotensin II, aldosterone and plasma converting enzyme activity had fallen, while blood angiotensin I and plasma renin activity had risen. Throughout the study, more than 90% inhibition of ACE was found immediately before giving either the 5 or 10 mg dose and 50% blockade was still present 72 h following the last dose. Based on the determination of ACE, there was no evidence of drug accumulation. No significant change in blood pressure or heart rate was observed during the course of the study. CGS 14824A was an effective, orally active, long-lasting and well tolerated converting enzyme inhibitor.

Individual responses to converting enzyme inhibitors and calcium antagonists.

This study was designed to assess whether the acute blood pressure response of an individual hypertensive patient to a calcium antagonist or an angiotensin converting enzyme (ACE) inhibitor is a good predictor of the long-term efficacy of these drug classes in this particular patient. The concept that good responses to ACE inhibitors and calcium antagonists may be mutually exclusive was also tested. Sixteen patients were included in a randomized crossover trial of enalapril, 20 mg daily, and diltiazem, 120 mg daily, for 6 weeks each. Blood pressure was measured by ambulatory blood pressure recording. During the washout phase, the acute effect of nifedipine, 10 mg p.o., and enalaprilat, 5 mg i.v., was evaluated. Nifedipine and enalaprilat reduced blood pressure equally well. The long-term blood pressure reduction induced by enalapril and diltiazem was similar. The acute blood pressure response to a given drug was not a good predictor of the result obtained with long-term therapy. No age dependency of the antihypertensive effect of either drug class was apparent. There was no evidence that a good response to one drug excluded a similarly good response to the other.

Effects of prolonged administration of the angiotensin converting enzyme inhibitor CGS 16617 in normotensive volunteers.

A new, orally active angiotensin converting enzyme (ACE) inhibitor, CGS 16617, has been evaluated in normotensive subjects during acute and prolonged administration. Single ascending doses of CGS 16617 20 to 100 mg were given to 9 normotensive volunteers at one week intervals and the changes in blood pressure, plasma ACE and renin activity were examined up to 72 h after drug intake. Also, CGS 16617 50 mg/day or placebo were given for 30 days to 8 and 6 normotensive subjects, respectively, maintained on an unrestricted salt diet. Blood pressure was measured daily in the office and ambulatory blood pressure profiles were also obtained before, during and after therapy, using the Remler M 2000 blood pressure recording system. CGS 16617 was an effective and long lasting ACE inhibitor. It did not induce a consistent change in blood pressure, but, the individual responses were very variable and several subjects experienced a clear decrease in the average of the blood pressures recorded during the daytime.

Renal hemodynamic and natriuretic effects of concomitant Angiotensin-converting enzyme and neutral endopeptidase inhibition in men.

This double-blind placebo-controlled study was designed to investigate the acute and sustained hormonal, renal hemodynamic, and tubular effects of concomitant ACE and neutral endopeptidase (NEP) inhibition by omapatrilat, a vasopeptidase inhibitor, in men. Thirty-two normotensive subjects were randomized to receive a placebo, omapatrilat (40 or 80 mg), or the fosinopril/hydrochlorothiazide (FOS/HCTZ; 20 and 12.5 mg, respectively) fixed combination for 1 week. Blood pressure, renal hemodynamics, urinary electrolytes and atrial natriuretic peptide excretion, and several components of the renin-angiotensin system were measured for 6 hours on days 1 and 7 of drug administration. When compared with the placebo and the FOS/HCTZ combination, omapatrilat induced a significant decrease in plasma angiotensin II levels (P<0.001 versus placebo; P<0.05 versus FOS/HCTZ) and an increase in urinary atrial natriuretic peptide excretion (P<0.01). These hormonal effects were associated with a significant fall in blood pressure (P<0.01) and a marked renal vasodilatation, but with no significant changes in glomerular filtration rate. The FOS/HCTZ markedly increased urinary sodium excretion (P<0.001). The acute natriuretic response to FOS/HCTZ was significantly greater than that observed with omapatrilat (P<0.01). Over 1 week, however, the cumulative sodium excretion induced by both doses of omapatrilat (P<0.01 versus placebo) was at least as great as that induced by the dose of FOS/HCTZ (P=NS versus FOS/HCTZ). In conclusion, the results of the present study in normal subjects demonstrate that omapatrilat has favorable renal hemodynamic effects. Omapatrilat combines potent ACE inhibition with a sustained natriuresis, which explains its well-documented potent antihypertensive efficacy.