In vitro and in vivo activity of R- and S- praziquantel enantiomers and the main human metabolite trans-4-hydroxy-praziquantel against Schistosoma haematobium

Praziquantel (PZQ) is the mainstay of schistosomiasis control and has been successfully used for decades. However, its mechanism of action is not fully understood. While the majority of studies have been conducted on Schistosoma mansoni, it is not known which enantiomer, R- or S-praziquantel (R-/S-PZQ), is responsible for the activity on Schistosoma haematobium.; In vitro and in vivo studies were conducted to evaluate the activity of R- and S-PZQ, racemic PZQ and the main human metabolite, namely trans-4-OH-PZQ, on S. haematobium. IC50 values on adult S. haematobium were determined in vitro. Dose-response relationship studies were performed in golden Syrian hamsters, harbouring a chronic S. haematobium infection.; R-PZQ displayed the highest activity against adult worms in vitro, revealing an IC50 of 0.007 μg/ml at 4 h and 0.01 μg/ml at 72 h. In contrast, S-PZQ was 501× less active (eudysmic ratio at 4 h), with an IC50 of 3.51 and 3.40 μg/ml (4 and 72 h, respectively). Racemic PZQ and trans-4-OH-PZQ resulted in an IC50 of 0.03 μg/ml and 1.47 μg/ml both at 4 and 72 h, respectively. In vivo, R-PZQ was the most potent drug with worm burden reductions (WBRs) of 98.5, 75.6 and 73.3% at 125.0, 62.5 and 31.0 mg/kg, respectively. A single oral dose of 250.0 mg/kg PZQ resulted in a WBR of 99.3%. S-PZQ was highly active in vivo at 250.0 and 500.0 mg/kg with WBRs of 83.0 and 94.1%, respectively. The lowest tested dose of S-PZQ, 125.0 mg/kg, showed moderate activity (WBR of 46.7%). The calculated ED50 for R- and S-PZQ were 24.7 and 127.6 mg/kg, respectively, with a corresponding eudysmic ratio of 5.17.; Our data support the theory of R-PZQ driving the antischistosomal activity. Interestingly, also S-PZQ proved to possess a significant activity towards S. haematobium, particularly in vivo

Preclinical and pharmacokinetic studies of praziquantel, the cornerstone of schistosomiasis treatment

Schistosomiasis remains the most important helminthic disease, infecting over 240 millions of people in tropical and subtropical areas of the world, while close to 800 millions of people live at risk of contracting it. Unfortunately, children are among the most affected and the disease often results in stunting, malnutrition and cognitive and physical retardation. Praziquantel (PZQ), being effective, cheap and safe, remains the cornerstone of schistosomiasis treatment and is distributed on a wide scale within drug administration programs. Until recently it was believed schistosomiasis among young children, below the age of six years, is not very common and consequently, they were not regularly treated. However, in 2011 WHO acknowledged these children are a risk group and could be included in the administration programs in the future, but pharmacokinetic data (PK), crucial to establish effective and safe dose of PZQ for pre-schoolers, is not readily available. Furthermore, in vitro and in vivo data on antischistosomal activity of PZQ for S. haematobium, responsible for the highest number of infections, is lacking. Moreover, PK studies in this sensitive population are tedious in conduct and call for a more patient friendly sampling approach, while the quality of sampling remains uncompromised. The aim of the present thesis was to gain more information about activity of both enantiomers of PZQ, R- and SPZQ, as well as the racemic drug and the main human metabolite (R-trans-4-hydroxy-PZQ) in vitro, in vivo and in humans. S. haematobium was studied in vitro and in vivo to evaluate and confirm its greater susceptibility to PZQ, compared to S. mansoni and S. japonicum. This species of schistosomes is characterised with a life-cycle, tedious to maintain in laboratory conditions and consequently, understudied compared to other species of the parasites. We determined IC50 values for racemic PZQ, both enantiomers and the main human metabolite on adult worms in vitro. Moreover, ED50 values for both enantiomers and the racemic drugs in hamster model were reported in vivo. In light of the development of paediatric formulation for PZQ, it would be important to evaluate how these findings translate to humans. Two PK studies were conducted within dose finding studies to investigate PK of both PZQ enantiomers and the main human metabolite. For the first time, PK parameters, such as area under the curve, maximal blood concentration and half-life of these analytes were revealed and compared. Influences, e.g. age and infection species on the PK processes were investigated. Moreover, a PK model for in depth study of influence on metabolic processes of RPZQ is currently under development. As a sub-study within SAC infected with S. haematobium, a novel micro-sampling device, called Mitra™, was evaluated in comparison to established dried blood spots technique, in the laboratory and under field conditions. A sample preparation method for PZQ with Mitra™ was established, optimised and validated in compliance with Food and Drug Administration guidelines. Owing to practicality and simplicity during both sampling and extraction process, Mitra™ showed great potential; however, overestimation of concentrations compared to dried blood spots in incurred, but not in spiked samples, is yet to be clarified. To conclude, we revealed PK parameters of the main entities, contributing to antischistosomal activity of PZQ. The PK model for RPZQ will reveal influences on metabolic processes of the proposed eutomer of PZQ. These findings will contribute to establishment and tailoring of guidelines for treating paediatric populations, infected with schistosomiasis, using PZQ. Validation of Mitra™ as a potential micro-sampling tool for PK studies will pave the way towards higher quality of sampling while maintaining high patient adherence. Last but not least, the study of S. haematobium in vitro and in vivo will compliment the existing data on activity of PZQ towards different species of schistosomes. Since SPZQ and the main human metabolite showed non-negligible activity towards S. haematobium, the decision whether to develop an enantio-pure paediatric formulation, consisting of RPZQ only, should be carefully evaluated

Efficacy and safety of praziquantel in preschool-aged and school-aged children infected with Schistosoma mansoni: a randomised controlled, parallel-group, dose-ranging, phase 2 trial

Background Praziquantel has been the drug of choice for schistosomiasis control for more than 40 years, yet surprisingly, the optimal dose for children younger than 4 years is not known. We aimed to assess the efficacy and safety of escalating praziquantel dosages in preschool-aged children (PSAC). Methods We did a randomised controlled, parallel-group, single-blind, dose-ranging, phase 2 trial in PSAC (2–5 years) and school-aged children (SAC; aged 6–15 years) as a comparator group in southern Côte d'Ivoire. Children were randomly assigned (1:1:1:1) to 20 mg/kg, 40 mg/kg, or 60 mg/kg praziquantel or placebo. Participants, investigators, and laboratory technicians were masked to group assignment, while the investigator providing treatment was aware of the treatment group. The primary objective was to estimate the nature of the dose–response relation in terms of cure rate using the Kato Katz technique. Dose–response curves were estimated using Emax models. Available case analysis was done including all participants with primary endpoint data. This trial is registered with International Standard Randomised Controlled Trial, number ISRCTN15280205. Findings Between Nov 11, 2014, and Feb 18, 2015, 660 PSAC and 225 SAC were assessed for eligibility; of whom 161 (24%) PSAC and 180 (80%) SAC had a detectable Schistosoma mansoni infection. 161 PSAC were randomly allocated of whom 154 received treatment: 42 were assigned to 20 mg/kg praziquantel, of whom 40 received treatment; 38 were assigned to 40 mg/kg praziquantel, of whom 38 received treatment; 41 were assigned to 60 mg/kg praziquantel, of whom 39 received treatment; and 40 were assigned to placebo, of whom 37 received placebo. 180 SAC were randomly allocated of whom 177 received treatment: 49 were assigned to 20 mg/kg praziquantel, of whom 47 received treatment; 46 were assigned to 40 mg/kg praziquantel, of whom 46 received treatment; 42 were assigned to 60 mg/kg praziquantel, of whom 42 received treatment; and 43 were assigned to placebo, of whom 43 received treatment. Follow-up (available-case) data were available for 143 PSAC and 174 SAC. In PSAC, the 20 mg/kg dose resulted in cure in 23 children (62%; 95% CI 44·8–77·5), 40 mg/kg in 26 children (72%; 54·8–85·8), 60 mg/kg in 25 children (71%; 53·7–85·4), and placebo in 13 children (37%; 21·5–55·1). In SAC, the 20 mg/kg dose resulted in cure in 14 children (30%; 95% CI 17·7–45·8), 40 mg/kg in 31 children (69%; 53·4–81·8), 60 mg/kg in 34 children (83%; 67·9–92·8), and placebo in five children (12%; 4·0–25·6). For both age groups, the number of adverse events was similar among the three praziquantel treatment groups, with fewer adverse events observed in the placebo groups. The most common adverse events in PSAC were diarrhoea (11 [9%] of 124) and stomach ache (ten [8%]) and in SAC were diarrhoea (50 [28%] of 177), stomach ache (66 [37%]), and vomiting (26 [15%]) 3 h post treatment. No serious adverse events were reported. Interpretation Praziquantel shows a flat dose-response and overall lower efficacy in PSAC compared with in SAC. In the absence of treatment alternatives, a single dose of praziquantel of 40 mg/kg, recommended by the WHO for S mansoni infections in SAC can be endorsed for PSAC in preventive chemotherapy programmes

Evaluation of the Clinitek®, a point-of-care urinalysis system for the measurement of clinically significant urinary metabolites and detection of haematuria in Schistosoma haematobium infected children in southern Côte d'Ivoire

Urinary schistosomiasis, caused by Schistosoma haematobium, remains a significant public health problem worldwide, despite years of efforts to control it. Haematuria is one of the notable indirect indicators of S. haematobium infection and is commonly assessed along with other routine screens using a urinary dipstick test. A portable "field friendly" electronic analyser would offer an automated and thus more objective read-out compared to visual-read dipstick methods.; Within the framework of a Phase 2 praziquantel dose finding study in preschool- and school-aged children infected with S. haematobium, in southern Côte d'Ivoire, we compared a visual-read of the urine dipstick strips (Multistix PRO, Siemens Healthcare Diagnostics) to an automated reader (CLINITEK Status+ analysertm Siemens Healthcare Diagnostics). Urine samples were collected from 148 pre-school aged and 152 school-aged children for urinalysis. Values were compared using a linear weighted kappa statistic and Bland-Altman analysis.; A very good correlation between the two methods for nitrites and haematuria was observed (κ coefficient of 0.88 and 0.82, respectively), while a good correlation was observed for leukocytes (κ coefficient of 0.63) A moderate to fair correlation was calculated (κ coefficient ≤ 0.6) for all other parameters. When the results were stratified according to infection intensity, the agreements were stronger from the high infection intensity sample measurements, for most of the parameters.; Our results demonstrate the device's utility in detecting haematuria and nitrites but underline the need for further development of this tool in order to improve its performance in the field

Efficacy and safety of ascending doses of praziquantel against Schistosoma haematobium infection in preschool-aged and school-aged children : a single-blind randomised controlled trial

Despite decades of experience with praziquantel treatment in school-aged children (SAC) and adults, we still face considerable knowledge gaps relevant to the successful treatment of preschool-aged children (PSAC). This study aimed to assess the efficacy and safety of escalating praziquantel dosages in PSAC infected with Schistosoma haematobium.; We conducted a randomised, dose-finding trial in PSAC (2-5 years) and as comparator a cohort of SAC (6-15 years) infected with S. haematobium in Côte d'Ivoire. A total of 186 PSAC and 195 SAC were randomly assigned to 20, 40 or 60 mg/kg praziquantel or placebo. The nature of the dose-response relationship in terms of cure rate (CR) was the primary objective. Egg reduction rate (ERR) and tolerability were secondary outcomes. CRs and ERRs were assessed using triplicate urine filtration over 3 consecutive days. Available-case analysis was performed including all participants with primary endpoint data.; A total of 170 PSAC and 174 SAC received treatment. Almost 90% of PSAC and three quarters of SAC were lightly infected with S. haematobium. Follow-up data were available for 157 PSAC and 166 SAC. In PSAC, CRs of praziquantel were 85.7% (30/35), 78.0% (32/41) and 68.3% (28/41) at 20, 40 and 60 mg/kg and 47.5% (19/40) for placebo. In SAC, CRs were 10.8% for placebo (4/37), 55.6% for 20 mg/kg (25/45), 68.3% for 40 mg/kg (28/41) and 60.5% for 60 mg/kg (26/43). ERRs based on geometric means ranged between 96.5% (60 mg/kg) and 98.3% (20 mg/kg) in PSAC and between 97.6% (20 mg/kg and 60 mg/kg) and 98.6% (40 mg/kg) in SAC. Adverse events were mild and transient.; Praziquantel revealed dose-independent efficacy against light infections of S. haematobium. Over the dose range tested, praziquantel displayed a ceiling effect with the highest response for 20 mg/kg in PSAC. In SAC maximum efficacy was obtained with 40 mg/kg praziquantel. Further investigations are required in children with moderate to heavy infections.; This trial is registered with International Standard Randomised Controlled Trial Number ISRCTN15280205

Ekspedicija Lukina jama - sifon 2013

Speleoronilačka ekspedicija u najdublju jamu u Hrvatskoj, Jamski sustav Lukina Jama - Trojamski, održana je od 2. do 25. kolovoza 2013. Ekspedicija Lukina jama - sifon 2013. organizirana je u svrhu istraživanja i topografskog snimanja sifona na dnu jame, izrade foto i video dokumentacije prostora jame i njene faune te prikupljanje geoloških i bioloških uzoraka. Ekspediciju su organizirali Speleološki klub Željezničar u suradnji s Udrugom Breganja, Nacionalnim parkom Sjeverni Velebit, Zagrebačkim speleološkim savezom, Hrvatskim biospeleološkim društvom, Hrvatskim speleološkim savezom, Komisijom za speleologiju Hrvatskog planinarskog saveza i Istarski speleološki savez. Vođa ekspedicije bio je Branko Jalžić-Bančo. Bazni logor je bio smješten u Velikom Lomu na sjevernom Velebitu. Organizacija i priprema započeli su početkom 2012. Prije ekspedicije bilo je puno posla, opremanja jame i podzemnih bivaka te postavljanje telefonske žice. Odaziv sudionika bio je velik i praktički nije bilo speleološkog kluba čiji članovi nisu sudjelovati na neki način. U ekspediciji su sudjelovali članovi 22 hrvatske i 10 stranih speleoloških udruga. Postignuti su svi ciljevi postavljeni za ekspediciju. Speleoronioci Vedran Jalžić i Petra Kovač Konrad zaronili su u sifon na dnu jame, uz tehničku pomoć Branka Jalžića i Alena Kirina. Jama je produbljena za 20 m, a trenutna dubina Jamskog sustava Lukina jama - Trojama iznosi -1431 m, što je čini 14. najdubljom jamom na svijetu. Izrađena je detaljan topografski nacrt te foto i video dokumentacija prostora. Tijekom ekspedicije prikupljen je, fotografiran i video snimljen vrijedan biološki materijal. Uzeti su uzorci pjeskovitog sedimenta za analizu sadržaja teških metala, kao i sedimenti s dna špilje i geološki uzorci. Uzorci vode i leda iz špilje uzeti su u svrhu analize stabilnih izotopa kisika i vodika. Stalni logeri za mjerenje razine vode, temperature i elektrolitske vodljivosti podzemne vode postavljeni su na sifonu i na 100 m i 200 m iznad dna. Obilni foto i video materijal posnimljen je od ulaza do samog dna jame

Poland, Slovenia, the World : Challenges of present-day education

Publikacja recenzowana / Peer-reviewed publicationTransformations of education in changing Europe are multifaceted. One of the latter is the process of strengthening the cooperation among universities in this part of the world. This cooperation is carried out in many fields – from joint projects and researches – to joint analyses, discourses and publications. This monograph – a collection of reflections, thoughts and polemics deriving from theoretical and empirical researches, carried out as a part of a joint research project simultaneously undertaken at both these universities under the name “Problems and challenges of modern education” – constitutes one of the fruits of the cooperation between Andrzej Frycz Modrzewski Cracow University and the University of Ljubljana