Sustained pacemaker function is a challenge in biological pacemaker engineering. Human cardiomyocyte progenitor cells (CMPCs) have exhibited extended survival in the heart after transplantation. We... Show moreSustained pacemaker function is a challenge in biological pacemaker engineering. Human cardiomyocyte progenitor cells (CMPCs) have exhibited extended survival in the heart after transplantation. We studied whether lentivirally transduced CMPCs that express the pacemaker current I-f (encoded by HCN4) can be used as functional gene delivery vehicle in biological pacing. Human CMPCs were isolated from fetal hearts using magnetic beads coated with Sca-1 antibody, cultured in nondifferentiating conditions, and transduced with a green fluorescent protein (GFP)- or HCN4-GFP-expressing lentivirus. A patch-clamp analysis showed a large hyperpolarization-activated, time-dependent inward current (-20 pA/pF at -140 mV, n = 14) with properties typical of I-f in HCN4-GFP-expressing CMPCs. Gap-junctional coupling between CMPCs and neonatal rat ventricular myocytes (NRVMs) was demonstrated by efficient dye transfer and changes in spontaneous beating activity. In organ explant cultures, the number of preparations showing spontaneous beating activity increased from 6.3% in CMPC/GFP-injected preparations to 68.2% in CMPC/HCN4-GFP-injected preparations (P < 0.05). Furthermore, in CMPC/HCN4-GFP-injected preparations, isoproterenol induced a significant reduction in cycle lengths from 648 +/- 169 to 392 +/- 71 ms (P < 0.05). In sum, CMPCs expressing HCN4-GFP functionally couple to NRVMs and induce physiologically controlled pacemaker activity and may therefore provide an attractive delivery platform for sustained pacemaker function. Show less
Over the last years major advances have been made in the field of C. difficile research. Despite the continuous progress of research in C. difficile epidemiology and molecular biology. This thesis... Show moreOver the last years major advances have been made in the field of C. difficile research. Despite the continuous progress of research in C. difficile epidemiology and molecular biology. This thesis shows that the development of molecular based techniques in detecetion and typing of C. difficile could be very valuable in combatting CDI. This also applies for the genetics and molecular biology of C. difficile in understanding the virulence of C. difficile. However, the continuing development of new techniques, both typing and genetics manipulation tools, has also led to the recognition of potential weaknesses of the currently frequent used techniques. Therefore, it is of utmost importance to keep up with the technical progress in the field of C. difficile research to enable further elucidation of the mechanisms that determine the virulence of C. difficile. Show less
Bakker, D.; Buckley, A.M.; Jong, A. de; Winden, V.J.C. van; Verhoeks, J.P.A.; Kuipers, O.P.; ... ; Corver, J. 2014
This dissertation presents the results of a computer-assisted linguistic analysis of the __Book of the Laws of the Countries__, a religious prose text, attributed to the 3rd-century theologian... Show moreThis dissertation presents the results of a computer-assisted linguistic analysis of the __Book of the Laws of the Countries__, a religious prose text, attributed to the 3rd-century theologian Bardaisan, which is one of the earliest representatives of Syriac literature. Using the computational tools and methods that were developed in the Leiden project __Turgama: Computer-Assisted Analysis of the Peshitta and the Targum: Text, Language and Interpretation__ by dr. Wido van Peursen, I have analysed this corpus on different linguistic levels: orthography / morphology, phrase structure, and clause structure. This analysis enables us to gain deeper insight in the peculiarities of the Syriac language of the 3rd century; the same period in which the Hebrew Bible was translated into Syriac, resulting in the so-called Peshitta. As such, the Book of the Laws of the Countries represents a corpus written in __native__ Syriac, to which the translated Syriac of the Peshitta can be compared. This will allow us to attain a better view of the considerations which played a role in the creation process of the Syriac Bible; e.g., the amount to which translation was influenced by interpretation, the two possible meanings of the Syriac word __Turgama__. Show less
In the past decade, the incidence of Clostridium difficile infections (CDI) with a more severe course has increased in Europe and North America. Assays that are capable of rapidly diagnosing CDI... Show moreIn the past decade, the incidence of Clostridium difficile infections (CDI) with a more severe course has increased in Europe and North America. Assays that are capable of rapidly diagnosing CDI are essential. Two real-time PCRs (LUMC and LvI) targeting C. difficile toxin genes (tcdB, and tcdA and tcdB, respectively) were compared with the BD GeneOhm PCR (targeting the tcdB gene), using cytotoxigenic culture as a gold standard. In addition, a real-time PCR targeting the tcdC frameshift mutation at position 117 (Delta 117 PCR) was evaluated for detecting toxigenic C. difficile and the presence of PCR ribotype 027 in stool samples. In total, 526 diarrheal samples were prospectively collected and included in the study. Compared with those for cytotoxigenic culture, sensitivity, specificity, positive predicted value (PPV), and negative predicted value (NPV) were for PCR LUMC 96.0%, 88.0%, 66.0%, and 98.9%, for PCR LvI 100.0%, 89.4%, 69.7%, and 100.0%, for PCR Delta 117 98.0%, 90.7%, 71.9%, and 99.5%, and for PCR BD GeneOhm 88.3%, 96.9%, 86.5%, and 97.4%. Compared to those with feces samples cultured positive for C. difficile type 027, the sensitivity, specificity, PPV, and NPV of the Delta 117 PCR were 95.2%, 96.2%, 87.0%, and 98.7%. We conclude that all real-time PCRs can be applied as a first screening test in an algorithm for diagnosing CDI. However, the low PPVs hinder the use of the assays as stand-alone tests. Furthermore, the Delta 117 PCR may provide valuable information for minimizing the spread of the epidemic C. difficile PCR ribotype 027. Show less
Totals of 102 and 56 Clostridium difficile type 078 strains of human and porcine origins, respectively, from four European countries were investigated by an optimized multilocus variable-number... Show moreTotals of 102 and 56 Clostridium difficile type 078 strains of human and porcine origins, respectively, from four European countries were investigated by an optimized multilocus variable-number tandem-repeat analysis (MLVA) and for tetracycline susceptibility. Eighty-five percent of all isolates were genetically related, irrespective of human or porcine origin. Human strains were significantly more resistant to tetracycline than porcine strains. All tetracycline-resistant strains contained the Tn916-like transposon harboring the tet(M) gene. We conclude that strains from human and porcine origins are genetically related, irrespective of the country of origin. This may reflect a lack of diversity and/or common source. Show less
The coincidental increase in norovirus outbreaks and Clostridium difficile infection (CDI) raised the question of whether these events could be related, e.g. by enhancing spread by diarrhoeal... Show moreThe coincidental increase in norovirus outbreaks and Clostridium difficile infection (CDI) raised the question of whether these events could be related, e.g. by enhancing spread by diarrhoeal disease outbreaks. Therefore, we studied the prevalence of C. difficile in outbreaks of viral gastroenteritis in nursing homes for the elderly and characterised enzyme immunoassay (EIA)-positive stool samples. Stool samples from nursing home residents (n = 752) in 137 outbreaks of viral aetiology were investigated by EIA for the presence of C. difficile toxins. Positive samples were further tested by a cell neutralisation cytotoxicity test, a second EIA and culture. Cultured isolates were tested for the presence of toxin genes, the production of toxins and characterised by 16S rRNA polymerase chain reaction (PCR) and sequencing. Twenty-four samples (3.2%) tested positive in the EIA. Of these 24 positive samples, only two were positive by cytotoxicity and three by a second EIA. Bacterial culture of 21 available stool samples yielded a toxinogenic C. difficile PCR ribotype 001 in one patient sample only. In conclusion, we found no evidence in this retrospective study for an association between viral gastroenteritis outbreaks and C. difficile. The high rate of false-positive EIA samples emphasises the need for second confirmation tests to diagnose CDI. Show less
De Europese Unie kampt met een imagoprobleem. Om de euroscepsis te verminderen, is het van belang te kunnen bewijzen wat de meerwaarde van een instituut als de EU is. Bovendien moeten politici zich... Show moreDe Europese Unie kampt met een imagoprobleem. Om de euroscepsis te verminderen, is het van belang te kunnen bewijzen wat de meerwaarde van een instituut als de EU is. Bovendien moeten politici zich niet meer aan verantwoordelijkheid op nationaal niveau onttrekken door 'Brussel' de schuld te geven van onpopulaire besluiten en aan te wijzen als beperkende factor van hun autonome beslissingsvrijheid. Wat dient er te veranderen om de EU weer aanzien te geven? Show less
