R-deprenyl: pharmacological spectrum of its activity.

Deprenyl has been discovered by Knoll and co-workers. The R-enantiomer of deprenyl (selegiline) is a selective and irreversible inhibitor of the B-isoform of monoamine oxidase (MAO-B) enzyme. Due to its dopamine potentiating and possible neuroprotective properties it has an established role in the treatment of parkinsonian patients. By inhibiting MAO-B enzyme, R-deprenyl decreases the formation of hydrogen peroxide, alleviating the oxidative stress also reduced by increased expression of antioxidant enzymes (superoxide dismutases and catalase) reported during chronic treatment. It was shown to prevent the detrimental effects of neurotoxins like MPTP and DSP-4. R-Deprenyl elicits neuroprotective and neuronal rescue activities in concentrations too low to inhibit MAO-B. It is extensively metabolized and some of the metabolites possess pharmacological activities, thus their contribution to neuroprotective properties was also suggested. The recently identified deprenyl-N-oxide is extensively studied in our laboratory. Effects other than neuroprotection, like influencing cell adhesion and proliferation cannot be neglected.

Deprenyl: from chemical synthesis to neuroprotection.

During the last decades (-)-deprenyl has become the golden standard of MAO-B inhibitors. It possesses dopamine potentiating and antioxidant properties; however, its effects cannot be explained solely by the enzyme inhibitory action. (-)-Deprenyl prevents the toxicity of certain selective neurotoxins and recently it was demonstrated to increase cell-cell adhesion as well. The complexity of its pharmacological effects reflects the action of both the parent compound and the active metabolites. (-)-Deprenyl and related propargylamines (DRPs) show neuroprotective features in a variety of in vitro and in vivo models that is dependent on the propargyl moiety. The main presumptive targets to date include glyceraldehyde-3-phosphate dehydrogenase, poly(ADP-ribose) polymerase, some kinase cascades, as well as pro- and antiapoptotic proteins, beside the inhibition of MAO-B. The antiapoptotic activity of DRPs converges upon the maintenance of mitochondrial integrity, due to the initiation of a complex transcriptional program, the details of which are yet to be elucidated.

Pharmacological aspects of (-)-deprenyl.

Deprenyl, the selective irreversible inhibitor of monoamine oxidase-B (MAO-B), has been synthesised as a potential antidepressant, however, due to its dopamine potentiating capacity, became a registered drug in the treatment of Parkinson's disease. Deprenyl possesses a wide range of pharmacological activities; some of them are not related to its MAO-B inhibitory potency. Beside its dopamine potentiating effect, it renders protection against a number of dopaminergic, cholinergic and noradrenergic neurotoxins with a complex mechanism of action. By inducing antioxidant enzymes and decreasing the formation of reactive oxygen species, deprenyl is able to combat an oxidative challenge implicated as a common causative factor in neurodegenerative diseases. In a dose substantially lower than required for MAO-B inhibition (10(-9)-10(-13) M), deprenyl interferes with early apoptotic signalling events induced by various kinds of insults in cell cultures of neuroectodermal origin, thus protecting cells from apoptotic death. Deprenyl requires metabolic conversion to a hitherto unidentified metabolite to exert its antiapoptotic effect, which serves to protect the integrity of the mitochondrion by inducing transcriptional and translational changes. Pharmacokinetic and metabolism studies have revealed that deprenyl undergoes intensive first pass metabolism, and its major metabolites also possess pharmacological activities. The ratio of the parent compound and its metabolites reaching the systemic circulation and the brain are highly dependent on the routes of administration. Therefore, in the treatment of neurodegenerative diseases, reconsideration of the dosing schedule, by lowering the dose of deprenyl and choosing the most appropriate route of administration, would diminish undesired adverse effects, with unaltered neuroprotective potency.

Altered nitric oxide production in mouse brain after administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridin or methamphetamine.

Several studies have demonstrated the involvement of reactive nitrogen and oxygen species (RNOS) in the neurotoxic effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridin (MPTP) and methamphetamine (METH), so the contribution of altered nitric oxide synthase (NOS) enzyme function can be suspected. In this study, about 50% increase in nitric oxide (NO) production in the mouse striatum was found between 4 and 12 h after a single MPTP injection, allowing an increased peroxynitrite (ONOO-) formation in the target brain region. However, METH injection induced a rapid decrease of NO formation both in mouse striatum and hippocampus, reaching its minimum level at 2 h, and restored to the control value after 6 h in the striatum and 12 h in the hippocampus. The uncoupled function of NOS with increased superoxide (O2*-) production after METH injection is suggested.

Studies on the insulinomimetic effects of benzylamine, exogenous substrate of semicarbazide-sensitive amine oxidase enzyme in streptozotocin induced diabetic rats.

Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO) is believed to be a bifunctional membrane protein. It is localized extracellularly and preferentially oxidizes short chain primary amines to aldehydes, hydrogen peroxide and ammonia, but also functions as an adhesion molecule, which is involved in leukocyte migration. Serum SSAO activity is increased in diabetic patients and animals and the aldehydes formed in the enzyme reaction may contribute to vascular damage. However, administration of exogenous substrates has been shown to improve glucose tolerance and reduce hyperglycaemia in diabetic animals. Hydrogen peroxide and/or its vanadate complexes have been suggested responsible for these effects. Streptozotocin induced diabetic rats were treated with benzylamine (BZA) +/- vanadate (V) or insulin. In contrast to insulin, BZA + V treatment did not reduce HbA(1C) levels. However, it reduced the elevated serum SSAO activity, decreased the accumulation of advanced-glycation end products and increased the bioavailability of nitric oxide in diabetic animals, similarly to insulin. BZA alone did not affect any of these parameters.

Placental transport of maternal immunoglobulin G.

PROBLEM: How does the placental transport of immunoglobulin G (IgG) vary with gestational age? METHOD OF STUDY: MEDLINE was searched for the appearance of "pregnancy" and "IgG" in the title or abstract from 1966 up to 1995. All publications were reviewed for any kind of IgG data from the fetus and the mother and "known" gestational age. In total, 96 publications from the MEDLINE search fulfilled the search criteria. Seven of ninety-six publications contained IgG and gestational age data from the fetus and/or the mother. Five other publications that fulfilled the same criteria were also available and were also included. RESULTS: Fetal serum IgG concentrations were found to increase with gestational age according to the formula: fetal IgG = 13.564 - 1.094 x gestational age (GA) + 0.026 x GA2 (R2 = 0.877). The fetomaternal (f/m) ratio was also found to increase with gestational age according to the formula: f/m IgG = 0.399 - 0.059 x GA + 0.003 x GA2 - 2.065 x 10(-5) x GA3 (R2 = 0.831). CONCLUSIONS: The fetal IgG concentrations exceed maternal IgG concentrations after the 35th week of pregnancy. The fetal IgG concentrations are extremely low in the beginning of pregnancy, they exceed 2.5 g/L at > 25 pregnancy weeks, and they reach 5 g/L at pregnancy week 30.

The frequency of anti-C + anti-G in the absence of anti-D in alloimmunized pregnancies.

Anti-D+C are often initially identified in sera from alloimmunized women. Anti-G may be present in these samples, mimicking anti-D+C, and therefore the differentiation of anti-D, -C and -G may be important. Sera from 27 alloimmunized women, initially identified as containing anti-D + anti-C, were analysed by adsorption/elution studies in the presence of polyethylene glycol (PEG) using R(0)r (D+C-G+) and r'r(D-C+G+) red blood cells (RBC). Additionally, 15/27 samples were tested by adsorption in the presence of PEG and subsequently warm elution, using rGr (D-C-G+) RBC. Anti-G + anti-C, without anti-D, were identified in 4/27 samples (14.8%) and none of the newborn children needed postpartum treatment. The combination of D+G, D+C and D+C+G antibodies occurred in 25.9%, 11.1% and 48.1% of the women, respectively. Overall, anti-G was detected in 24/27 samples (88.9%). Pregnant women shown to have anti-G+C but not anti-D should receive Rh immune globulin. Additionally, the finding of apparent anti-D+C during pregnancy in D-negative spouses may lead to paternity testing and therefore a correct antibody identification is necessary.

Application of the gel test in IgG subclassing--a comparison of two agglutination assays.

BACKGROUND AND OBJECTIVES: IgG subclasses of anti-D seem to play some role in hemolytic disease of the newborn, but there has been disagreement as to its exact nature. The aim of our study was to evaluate a new technique for IgG subclassing of anti-D and to compare it to an established test. MATERIALS AND METHODS: In 31 cases of RhD immunization, we have compared two simple agglutinating assays for subclassing anti-D: an established V-well microtiter tray assay and a new gel test assay. Polyclonal rabbit anti-IgG agglutinating antibodies were tested against sensitized D-positive red blood cells by both assays. RESULTS: The anti-D concentration in tested sera varied between 0.1 and 81 micrograms/ml (0.5-405 IU/ml). Both assays were simple to perform and the results correlated well. CONCLUSIONS: The gel test had two advantages: quick performance and easy interpretation.

A randomized controlled trial oftransfusion-related acute lung injury: is plasma from multiparous blood donors dangerous?

BACKGROUND: Transfusion-related acute lung injury (TRALI) and other posttransfusion reactions may be caused by granulocyte and/or HLA antibodies, which are often present in blood from multiparous donors. The purpose of this study was to compare the effects of plasma from multiparous donors with those of plasma from donors with no history of transfusion or pregnancy (control plasma) in a prospective, randomized, double-blind, crossover study. STUDY DESIGN AND METHODS: Intensive care patients, judged to need at least 2 units of plasma, were randomly assigned to receive a unit of control plasma and, 4 hours later, a plasma unit from a multiparous donor (> or = 3 live births) or to receive the plasma units in opposite order. The patients were closely monitored, and body temperature, blood pressure, and heart rate were recorded. Blood samples for analysis of blood gases, TNFalpha, IL-1 receptor antagonist, soluble E selectin, and C3d complement factor were collected at least on four occasions (before and after the transfusion of each unit). RESULTS: Transfusion of plasma from multiparous donors was associated with significantly lower oxygen saturation and higher TNFalpha concentrations than transfusion of control plasma. The mean arterial pressure increased significantly after the transfusion of control plasma, whereas plasma from multiparous donors had no effect on it. Five posttransfusion reactions were observed in 100 patients, in four cases after the transfusion of plasma from multiparous donors. CONCLUSION: Plasma from multiparous blood donors may impair pulmonary function in intensive care unit patients.

Placental transport of maternal immunoglobulin G in pregnancies at risk of Rh (D) hemolytic disease of the newborn.

PROBLEM: The following questions were addressed: Is the placental transport of immunoglobulin (Ig)G, IgG1, and IgG3 diminished in pregnancies at risk of hemolytic disease of the newborn? Is the placental transport of IgG, IgG1, and IgG3 correlated with the hemoglobin concentration in the fetus and AutoAnalyzer (AA) quantitations of maternal anti-D? METHOD OF STUDY: IgG concentrations were determined retrospectively in 41 paired fetal/maternal (f/m) samples in 31 Rh (D) alloimmunized pregnancies. IgG1 and IgG3 concentrations were determined in those 23 cases in which the results of fetal hemoglobin concentration and quantitations of maternal anti-D were available. The results were compared with values found in normal pregnancy and correlated with maternal anti-D AA quantitations and fetal hemoglobin concentrations. RESULTS: Fetal IgG, IgG1, and IgG3 concentrations, and the corresponding fetomaternal ratios in Rh (D) alloimmunized pregnancies, increased with gestational age according to the following formulas (obtained by simple regression): Fetal IgG = -8.846 + 0.491.gestational age (GA), (R2 = 0.544); fetal IgG = 10.021 + 0.46.GA (R2 = 0.463); fetal IgG3 = -0.865 + 0.039.GA, (R2 = 0.327); f/m IgG = -1.006 + 0.054.GA, (R2 = 0.557); f/m IgG1 = -1.876 + 0.085.GA, (R2 = 0.654); f/m IgG3 = -0.199 + 0.026.GA, (R2 = 0.146). CONCLUSIONS: The placental transport of IgG, IgG1, and IgG3 in women with Rh (D) immunizations is not diminished compared with normal pregnancy. However, AA quantitations of anti-D are inversely correlated with f/m IgG ratio, f/m IgG1 ratio, and fetal IgG and IgG1 concentrations (P = 0.002, P = 0.004, P = 0.02, and P = 0.02 respectively). The placental transport of IgG3 is significantly higher in pregnancies at risk of hemolytic disease of the newborn compared with IgG3 concentrations in normal pregnancy.

Circulating interferon-gamma- and interleukin-4-secreting cells in recurrent spontaneous abortions.

PROBLEM: Are recurrent spontaneous abortions (RSAs) associated with deviation of circulating cytokine-secreting cells? METHOD OF STUDY: Interferon (IFN)-gamma- and interleukin (IL)-4 secreting cells were identified by enzyme-linked immunospot (ELISPOT) in blood from 34 women with RSA. Samples were taken before pregnancy and/or pregnancy weeks 7-10, 17-20, and after terminated pregnancy. Eleven healthy primigravidae and 10 non-pregnant women served as controls. RESULTS: No significant difference in numbers of IFN-gamma- and IL-4-secreting cells was noted within the RSA group when abortions and successful pregnancies were compared in samples taken before pregnancy. The number of IFN-gamma- as well as IL-4-secreting cells in pregnancy weeks 17-20 in the RSA group was significantly higher compared with before pregnancy, pregnancy weeks 7-10, and after pregnancy. In samples from non-pregnant women, the number of IFN-gamma- and IL-4-secreting cells was significantly higher in the RSA group compared with controls. CONCLUSIONS: Our results do not indicate a systemic shift in the general balance between T helper 1- and T helper 2-type cytokine pattern. A local shift at the fetomaternal interface seems more probable.

Blocking antibodies in blood from patients with recurrent spontaneous abortion in relation to pregnancy outcome and intravenous immunoglobulin treatment.

PROBLEM: To study whether the occurrence of mixed lymphocyte culture (MLC) blocking antibodies is associated with pregnancy outcome in women with unexplained recurrent spontaneous abortion (RSA) and the in vivo effect of intravenous immunoglobulin (IVIG) treatment on MLC blocking effect. METHOD OF STUDY: Blood samples from 41 RSA patients were obtained before and after pregnancy, and blocking antibodies were estimated by one-way MLC assay. The patients received IVIG or placebo (saline) during pregnancy. Additionally, prepregnancy blood samples from 31 RSA women and 10 controls were obtained. RESULTS: We found no correlation between blocking antibodies before pregnancy and the pregnancy outcome. The occurrence of blocking antibodies was not affected by pregnancy or IVIG treatment. CONCLUSIONS: Blocking antibodies have no predictive value for the pregnancy outcome in RSA patients, and their production seems not to be affected by IVIG.

Prevention of recurrent spontaneous abortion by intravenous immunoglobulin: a double-blind placebo-controlled study.

The aim of this study was to evaluate the therapeutic efficacy of intravenous immunoglobulin (IVIG) in the prevention of recurrent spontaneous abortion (RSA). In a double-blind, randomized, placebo-controlled study, 41 women with a history of unexplained recurrent spontaneous abortion were treated with IVIG or saline infusions during pregnancy. The birth of a child was considered a successful outcome. The overall success rate was 77% in the IVIG group compared with 79% in the placebo group. For women with primary RSA the success rates were 82 (IVIG) and 89% (placebo), and for women with secondary RSA the rates were 73 (IVIG) and 70% (placebo). We found no statistically significant difference in treatment results between IVIG and placebo.