Lowered cAMP and cGMP signalling in the brain during levodopa-induced dyskinesias in hemiparkinsonian rats: new aspects in the pathogenetic mechanisms

Dysregulation of dopamine receptors is thought to underlie levodopa-induced dyskinesias in experimental models of Parkinson's disease. It is unknown whether an imbalance of the second messengers, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), is involved in the alterations of levodopa/dopamine signal transduction. We examined cAMP and cGMP signalling in the interconnected cortico-striatal-pallidal loop at the peak of levodopa-induced dyskinesias in rats with 6-hydroxydopamine lesions in the substantia nigra. In addition, we examined the role of phosphodiesterase (PDE) and the rate of cAMP and cGMP degradation on the severity of levodopa-induced dyskinesias in animals pretreated with PDE inhibitor, zaprinast. Unilateral lesion of substantia nigra led to an increase in cAMP but a decrease in cGMP levels in the ipsilateral basal ganglia. After chronic levodopa treatment, cAMP and cGMP were differentially regulated in eukinetic animals: the cAMP level increased in the cortex and striatum but decreased in the globus pallidus of both hemispheres, whereas the cGMP decreased below baseline levels in the contralateral cortico-striatal-pallidal regions. In dyskinetic animals chronic levodopa treatment led to an absolute decrease in cAMP and cGMP levels in cortico-striatal-pallidal regions of both hemispheres. Pretreatment with zaprinast reduced the severity of levodopa-induced dyskinesias, and partly prevented the decrease in cyclic nucleotides compared with pretreatment with saline-levodopa. In conclusion, using a rat model of hemiparkinsonism, we observed a significant reduction in the levels of cyclic nucleotides in both hemispheres at the peak of levodopa-induced dyskinesias. We propose that such a decrease in cyclic nucleotides may partly result from increased catabolism through PDE overactivity.

RANTES and human sperm fertilizing ability: effect on acrosome reaction and sperm/oocyte fusion

Beta-chemokine, regulated on activation and normally T-cell expressed and presumably secreted (RANTES), is present in both the male and female genital tract fluids where its levels increase in diseases related to infertility, such as endometriosis and male genital tract infections. beta-Chemokine receptors (CCR3 and CCR5) are expressed on freshly ejaculated human sperm cells and a sperm chemoattractant effect for RANTES has been reported. No information exists on other possible roles of RANTES on sperm functions involved in the fertilization process. In the present study, the exposure of sperm suspensions to high concentrations of the chemokine, comparable to those observed in inflammatory diseases, significantly decreased the stimulatory effect exerted by progesterone on sperm/oocyte fusion, evaluated by means of the hamster egg penetration test. Accordingly, a large proportion of spermatozoa preincubated under capacitating conditions with high concentrations of RANTES underwent a premature acrosome reaction (AR) that prevented subsequent progesterone-induced AR. Finally, sperm samples exposed to the same high levels of chemokine showed a significant increase in the intracellular levels of cAMP, which is involved in capacitation and AR dynamics. These results indicate a negative interference of high levels of RANTES on the sperm fertilizing ability, thereby suggesting a potential contribution of this chemokine to subfertility associated with endometriosis and genital tract inflammatory diseases.

Better Mycophenolic Acid 12-Hour Trough Level After Enteric-Coated Mycophenolate Sodium in Patients With Gastrointestinal Intolerance to Mycophenolate Mofetil

INTRODUCTION

Enteric-coated mycophenolate sodium (EC-MPS) is the enteric-coated salt form of mycophenolic acid (MPA), the active component of the prodrug mycophenolate mofetil. EC-MPS was developed to reduce the upper-gastrointestinal (GI) effects of mycophenolate mofetil. There are no studies available comparing trough plasma levels in patients with GI intolerance to MMF when they are converted to EC-MPS.

AIM

To compare the GI tolerance and the MPA levels in patients previously treated with MMF in whom this drug was replaced by EC-MPS.

MATERIALS AND METHODS

A prospective study was conducted in 133 renal transplant patients after conversion from MMF to EC-MPS (median time posttransplant 42 months, range 1 to 240 months). The causes for EC-MPS switching were GI intolerance to MMF (51.9%; group A), low trough plasma levels with MMF (29.3%; group B), and others (18.8%; group C). These patients were converted to equipotent doses of EC-MPS.

RESULTS

The trough plasma MPA levels increased from 1.5 +/- 1.1 microg/mL at baseline to 2.5 +/- 2.0 microg/mL at 1 month postconversion despite the equipotent EC-MPS doses not being increased. These higher plasma levels were maintained throughout the study. In group A, this increase was from 1.8 +/- 1.0 to 2.7 +/- 2.1 microg/mL (P = .01) and in group B from 0.8 +/- 0.4 to 2.4 +/- 1.4 microg/mL (P < .001). The doses and levels of calcineurin inhibitor decreased from baseline. Creatinine clearance improved from 56.5 +/- 24.7 mg/dL at baseline to 61.9 +/- 28.6 at 6 months postconversion (P = .02). There was a statistically significant increase in hemoglobin levels. In group A, the GI tolerance improved in 78% of the patients.

CONCLUSIONS

At equipotent doses, patients converted to EC-MPS have higher and more adequate levels of MPA. At 6 months postconversion, we observed an improvement of the renal function, probably due to a reduction of calcineurin inhibitor drugs. However, the possibility that a better immunosuppressive efficacy as demonstrated by more suitable trough plasma levels may have been a contributing factor cannot be discarded.

Study of Anemia After Late Introduction of Everolimus in the Immunosuppressive Treatment of Renal Transplant Patients

INTRODUCTION

mTOR inhibitors (imTOR) are immunosuppressive drugs that have a concentration-related effects on hematopoiesis, potentially resulting in anemia. The reason is uncertain, but a pathogenic link between sirolimus-induced anemia and the appearance of an inflammatory state was recently suggested. Because inflammation-related anemia is characterized by a functional iron deficiency, we studied whether everolimus influenced iron homeostasis.

METHODS

We studied iron homeostasis in 43 patients after late introduction of everolimus into the immunosuppressive treatment. Thirty-seven patients (86%) were receiving mycophenolate. Hemoglobin concentration, red blood cell count, mean corpuscular volume, serum iron, ferritin, C-reactive protein levels, and transferrin saturation were evaluated 3 months before and 1, 3, and 6 months after the switch.

RESULTS

The percentage of anemic patients preconversion was 18.6% and it was 34.9% at 3 months and 18.6% at 6 months. We did not observe a significant reduction in hemoglobin, but there was increased red blood cell count after everolimus introduction, with a significant reduction in mean corpuscular volume. Serum iron and transferrin saturation levels were also markedly reduced after the switch, while ferritin serum concentrations remained stable. An improvement in renal function was observed.

CONCLUSIONS

The anemia caused by everolimus--microcytosis, low serum iron, despite high ferritinemia, and elevated C-reactive protein levels--was consistent with the anemia of a chronic inflammatory state. This alteration occurred within the first months postconversion and disappeared at 6 months. The combination of mycophenolate and everolimus seemed to be useful without significant secondary effects.

[Diagnosis and insurance compensation of occupational diseases in construction industry]

The aim of this study is to evaluate the outcome of 302 occupational diseases in building workers detected by UOOML Ospedali Riuniti of Bergamo and notified to INAIL from 2000 to 2005. The 41.3% of cases were accepted as work-related. Among remaining cases (58.7%), INAIL rejected 40.9% for lack or absence of documentation. 59.1% for no adhesion to legal medicine criteria. By analysis of occupational diseases detected in the last 5 years, we found an increase of muscle-skeletal disorders, for which, now, diagnostic procedure and insurance evaluation are difficult. This work shows a wide gap between reported occupational diseases of buildings workers and compensation given by INAIL. These results underlines the need of comparison among involved institutions in order to standardize statistical and diagnostic instruments.

First Insights into the Electronic Properties of a Cu(II) Center Embedded in the PN3 Cap of a Calix[6]arene-Based Ligand

The first metal complex based on the calix[6]PN3 cryptand is described. The solid-state and solution studies show a 5-coordinate Cu(II) center due to its coordination to the PN3 cap and to an exchangeable guest molecule. Spectroscopic and electrochemical studies evidence surprising properties of the metal ion, which are tentatively assigned to the unusual P-Cu(II) bond enforced by the cryptand.

Crystal structure of μ-dichlorobis(N-benzyl-bis(2-pyridylmethyl) amino)dicopper(II) diperchlorate ethanol solvate (1:⅔), [Cu2Cl2{N(C6H6N)2(C7H7)}2][ClO4]2 · ⅔ C2H5OH

C39.33H42Cl4Cu2N6O8.67, trigonal, R3̅ (no. 148), a = 27.819(4) Å, c = 14.447(6) Å, V = 9682.8 Å3, Z = 9, Rgt(F) = 0.040, wRref(F2) = 0.109, T = 293 K.

Absolute configuration and conformational disorder of a tricyclic thiosemicarbazone derivative

The title compound, (1S,3R,8R)-2,2-dichloro-3,7,7,10-tetramethyltricyclo[6.4.0.0(1,3)]dodecan-11-one thiosemicarbazone, C17H25Cl2N3S, has two disordered conformations of the cycloheptane moiety and a screw-boat conformation for the cyclohexene ring. The absolute configuration was established.

First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

A New HPLC Method to Determine Glomerular Filtration Rate and Effective Renal Plasma Flow in Conscious Dogs by Single Intravenous Administration of Iohexol and p-Aminohippuric Acid

A high-performance liquid chromatography method to determine iohexol (IOX) and p-aminohippuric acid (PAH) in the plasma of dogs is evaluated according to recovery, reproducibility, and linearity utilizing a gradient pump. The mobile phase consists of 50mM sodium dihydrogen phosphate with 0.5mM tetrabutylammonium chloride, the pH is adjusted to 4.1, methanol is added to the final ratio of 90:10 (v/v), the flow rate is set at 1 mL/min, and separation is achieved with an ODS2 Luna column. The UV detector is set at 254 nm. IOX and PAH are used for evaluation of the effective renal plasma flow (ERPF) and glomerular filtration rate (GFR). The present method tested in three dogs demonstrates the accuracy in the evaluation of ERPF and GFR. Because of its precision and simplicity and low cost, it can be considered a good tool for ERPF and GFR in small animal practice.

Inhibition of cytochrome p450 enzymes by enrofloxacin in the sea bass (Dicentrarchus labrax)

Currently, there are no reports on the effects of enrofloxacin (EF), a fluoroquinolone antibiotic, on the cytochrome p450 enzymes in fish, although its use as antimicrobial agent in aquaculture has been put forward. Therefore, the in vivo and in vitro effects of EF on hepatic p450 enzymes of sea bass, a widespread food-producing fish, have been evaluated. Sea bass pretreated with a single dose of EF (3 mg/kg i.p.) or with three daily doses of EF (1 mg/kg i.p.) markedly depressed the microsomal N-demethylation of aminopyrine, erythromycin, the O-deethylation of 7-ethoxycoumarin, ethoxyresorufin and the 6beta-testosterone hydroxylase. In vitro experiments showed that EF at 10 microM inhibited the above-mentioned activities and, in particular, the erythromycin N-demethylase (ERND) and 6beta-testosterone-hydroxylase, likely dependant on a p450 3A isoform. When the nature of ERND inhibition by EF was specifically studied with sea bass liver microsomes, it was found that EF is a potent mechanism-based inhibitor, with K(i) of 3.7 microM and a K(inact) of 0.045 min(-1). An immunoblot analysis with anti p450 3A27 of trout showed that the p450 3A isoform, constitutively expressed in sea bass, is particularly susceptible to inactivation by EF. In vitro experiments with sea bass microsomes have also demonstrated that EF is oxidative deethylated by the p450 system to ciprofloxacin (CF) and that this compound maintains the ability to inactivate the p450 enzymes. The mechanism by which EF or CF inactivate the p450 enzymes has not been studied but an attack of p450 on the cyclopropan ring, present, both in EF and CF structure, with the formation of electrophilic intermediates (i.e. radicals) has been postulated. In conclusion, the EF seems to be a powerful inhibitor of p450s in the sea bass. Therefore, the clinical use of this antibiotic in aquaculture has to be considered with caution.

Effects of liquid and freeze-dried grapefruit juice on the pharmacokinetics of praziquantel and its metabolite 4′-hydroxy praziquantel in beagle dogs

Grapefruit juice changes the pharmacokinetic parameters of a variety of drugs metabolized primarily by cytochrome P450 3A. In a three-phase crossover study, six male beagle dogs were administered 100 ml of water (control), 100 ml of commercial liquid grapefruit juice, or 10 g of freeze-dried grapefruit juice (equivalent to 100 ml of liquid grapefruit juice) with 100 ml of water, followed after 2 h by single oral dose of praziquantel (30 mg kg(-1)). After treatment, the dogs were sampled at different times. Determination of praziquantel and its metabolite 4'-hydroxy praziquantel (identified by GC/MS) was performed by HPLC. Liquid and freeze-dried grapefruit juice preadministration increased the C(max) of praziquantel about three-fold and the AUC 2.5- and 2.3-fold, respectively. The T(max) (0.75 h) was unaffected by liquid or freeze-dried grapefruit juice, while T(1/2) was 2.3- and 1.7-fold higher compared with controls. The amount of 4'-hydroxy praziquantel was also affected by both liquid and freeze-dried grapefruit juice administration: the AUC and C(max) increased four- and three-fold, respectively and the T(max) was significantly enhanced. These findings demonstrate that both freeze-dried grapefruit juice and commercial liquid grapefruit juice significantly increase plasma concentrations and T(1/2) of praziquantel in dogs.