In vitro assessment of artesunate, artemether and amodiaquine susceptibility and molecular analysis of putative resistance-associated mutations of Plasmodium falciparum from São Tomé and Príncipe

Objective To evaluate the basal in vitro responses of Plasmodium falciparum isolates collected in The Democratic Republic of São Tomé and Príncipe to artemether (ATH), artesunate (ATN) and amodiaquine (AMQ). Methods The prevalence of given single nucleotide polymorphisms in the pfmdr1, pfcrt, pftctp and pfATPase6 genes was assessed by PCR‐RFLP or DNA sequencing, and gene copy numbers were estimated by real‐time PCR. Results Mean IC50s to ATH and ATN were relatively low (1.12 nm and 0.58 nm, respectively). However, 10% of parasites displayed AMQ IC50 values above the accepted resistance threshold of 60 nm and there was a positive association between susceptibility to all three drugs (ATH vs. ATN: R = 0.84; ATH vs. AMQ: R = 0.68; ATN vs. AMQ: R = 0.72). Mutations in the pfcrt and pfmdr1 genes were highly prevalent, while only one synonymous polymorphism was detected in the pfATPase6 gene and no mutations were found in pftctp. All isolates harboured a single copy of the genes studied. Conclusions Artemisinin combination treatment in the São Tomé and Príncipe should be efficacious, although a significant number of AMQ‐resistant parasites were detected and the susceptibility to each drug was positively associated with that of the other two. Mutations in the pfcrt and pfmdr1 genes are near fixation, most likely because of high levels of chloroquine resistance, whereas only one protein type of the artemisinin resistance candidate, PfATPase6, was identified.     

Western blot analysis of human and rat serotonin transporter in platelets and brain using site-specific antibodies: evidence that transporter undergoes endoproteolytic cleavage

BACKGROUND: Serotonin transporter (SERT) is important target molecule for many antidepressive drugs and substances of abuse and is implicated in psychiatric disorders. We performed immunoblotting analysis of human and rat SERT in platelets and brain using the panel of eight site-specific SERT monoclonal and polyclonal antibodies (mAbs and pAbs). METHODS: SDS-PAGE/Western blotting was conducted using peroxidase-labeled DEAE and affinity purified SERT antibodies under conditions preventing SERT post-extraction degradation. RESULTS: Immunoreactive polypeptides of 14, 22, 32, 35, 37, 56, 68, and approximately 150-200 kDa were revealed in human platelet extracts using N-terminal and C-terminal SERT antibodies. In rat brain, C-terminal mAbs detected 68, 56, and 37 kDa proteins, in postmortem human brain predominated 35-37 kDa proteins. The immunoreactivity was abolished after antibody preadsorption with antigens. N-terminal pAbs recognized the 68 kDa protein, affinity purified on C-terminal mAbs, confirming its identity as full-size human SERT (the predicted size approximately 70.5 kDa). CONCLUSIONS: The explanation of the results of immunoblotting most likely is a site-specific SERT endoproteolytic cleavage and a marked difference in glycosylation rather than nonspecific protein degradation, cross-reactivity with other epitopes or SERT alternative splicing.     

Plasma levels of clozapine and norclozapine in Mexican schizophrenia patients

The aim of the present study was to determine the prescribing practice for clozapine (CAS 5786-21-0) as well as the plasma levels of clozapine and its main metabolite norclozapine (CAS 6104-71-8) in Mexican patients. A prospective study was performed in 69 in and out psychotic patients taking clozapine. Blood samples were taken at steady state. Plasma concentrations of clozapine and norclozapine were determined by HPLC. The results showed that the mean daily dose administered was 250 mg/d. Plasma levels showed a large interindividual variability. Mean plasma levels were 411.3 +/- 328.12 ng/mL, for clozapine and 172.0 +/- 129.9 ng/mL for norclozapine. When data were compared with those reported in other populations, it was found that although the dose was lower than that reported in Caucasians, the plasma levels were similar. As a result, the predictive models for the estimation of clozapine concentration in Caucasians were not appropriate for application in Mexican patients. The findings suggest ethnic differences in the ratio dose/plasma levels of clozapine in Mexican patients. Further studies are required to expand the observations.     

Pharmacokinetics of HEPP, a new anticonvulsant, in healthy subjects and rabbits after multiple doses

In the present study the pharmacokinetics of D,L-3hydroxy-3-phenylpropionamide (HEPP) a new anticonvulsant compound was studied after multiple dose administration in healthy male volunteers and in rabbits. The study in humans involved the oral administration of 375 mg of HEPP b.i.d. for 7 consecutive days. The study in rabbits explored doses of 30 mg/kg intraperitoneal (i.p.) given once daily for 6 days. In both studies pharmacokinetic (PK) profiles were characterized after the first dose and after the last multiple dose. Plasma HEPP concentrations were measured by HPLC. Pharmacokinetic parameters were calculated by noncompartmental methods. The results in humans as well as in rabbits showed that after multiple doses the AUC values decreased and CL/F values were significantly increased, which could be due to an induction process in the metabolic disposition of the drug.     

Molsidomine modulates the cNOS activity in an experimental model of cholinergic damage induced by 192-IgG saporin

The aim of this work was to study the effect of molsidomine (MOLS), a nitric oxide (NO) donor, on the nitrergic system changes in an experimental model of cholinergic damage induced by 192 IgG saporin (SAP). Male rats were injured by intraseptal administration of SAP (0.22 μg), after seven days, rats were administered with MOLS (4 mg/kg, i.p.) 60 min before sacrifice. Prefrontal cortex (PC), striatum (S) and hippocampus (HC) were dissected out. Results showed significant recovery of the constitutive NOS activity (cNOS) in PC and S regions by MOLS but not in HC compared against controls. SAP reduced the cellular population in the lesion site and MOLS was able to avoid the progression of damage in this area. NO donor is able to modulate the nitrergic status in an experimental model induced by SAP.     

In vitro effects of albendazole sulfoxide and praziquantel against Taenia solium and Taenia crassiceps cysts

We investigated the minimum exposure times of prazicuantel (PZQ) and albendazole sulfoxide (ABZSO) required for their activities against Taenia cysts in vitro as well as the 50 and 99% effective concentrations. The results showed that although the effects of both drugs are time and concentration dependent, ABZSO acts much slower and is less potent than PZQ.     

Molsidomine modulates the cNOS activity in an experimental model of cholinergic damage induced by 192-IgG saporin

Postural control strategies are frequently assessed through posturography on a firm surface. Their motor efficiency is related to the coordination between center-of-gravity (CG) and center-of-pressure (CP) movements, which results from long-term training. However, when standing on a seesaw favoring pitching body motions, a new coordination, requiring short-term training, needs to be learned again. On this type of device, somesthetic cues from the ankle joints become invalid and motor command is amplified because of the curvature of the contact ridges. To highlight the mechanisms involved in short-term improvements of postural control, 11 healthy young adults were trained for 20 min by standing on a seesaw with their eyes closed. Two series of posturographic measurements, before and after the training, were recorded whilst the subjects stood on the seesaw with eyes closed. The results indicate a reduction in the horizontal CG displacements along the anteroposterior axis and CP-CG displacements along both anteroposterior and mediolateral axes. Fractional Brownian motion (fBm) analysis further explains these lessened CG movements by highlighting a reduced distance covered before the corrective mechanisms take over. The other fBm parameters, the contribution of stochastic activity during the shortest and longest time intervals or the time interval of the transition points (which expresses the mean delay before the corrective mechanisms take over), remained unchanged. These results could likely be explained by reduced tonic muscular activity of the lower limbs and/or recalibration of the sensory systems in order to improve the detection of the CG movements.     

Comparative analysis of the influence of food and cimetidine in plasma levels of praziquantel

Praziquantel (PZQ) is an effective drug for treatment of neurocysticercosis. The drug shows an extensive first-pass effect and therefore plasma levels are low. In order to increase plasma and CSF levels of PZQ other alternatives have been investigated such as the use of PZQ jointly with cimetidine or food. With the pharmacokinetic parameters obtained in these studies, in the present work computer simulations were made in order to predict plasma concentrations of PZQ-administration with cimetidine or with meals under the two treatments currently used: ultrashort scheme (three dose of 25 mg/kg given at 2-hours intervals) and the traditional scheme (50 mg/kg/day divided in three dose given at 8-hours intervals for 15 days). The results of our simulations showed that the combination of PZQ with a high carbohydrate diet could be an adequate alternative for clinical therapy. Furthermore a clinical study was performed in 18 patients with neurocysticercosis, which received the ultrashort scheme in fasting state, with cimetidine or with a high carbohydrate diet. The efficacy of the treatment was evaluated by the percentage of disappearance of the lesions and plasma levels obtained in each group. The results showed that a high carbohydrate diet increases plasma levels of PZQ. The results of the clinical study, together with our simulations indicate that the treatment of PZQ with a high carbohydrate diet was an adequate clinical alternative and showed improvement of the effectiveness of PZQ therapy.     

Redox and Anti-Inflammatory Properties from Hop Components in Beer-Related to Neuroprotection

Beer is a fermented beverage widely consumed worldwide with high nutritional and biological value due to its bioactive components. It has been described that both alcoholic and non-alcoholic beer have several nutrients derived from their ingredients including vitamins, minerals, proteins, carbohydrates, and antioxidants that make beer a potential functional supplement. Some of these compounds possess redox, anti-inflammatory and anticarcinogenic properties making the benefits of moderate beer consumption an attractive way to improve human health. Specifically, the hop cones used for beer brewing provide essential oils, bitter acids and flavonoids that are potent antioxidants and immune response modulators. This review focuses on the redox and anti-inflammatory properties of hop derivatives and summarizes the current knowledge of their neuroprotective effects.