PubMed Health⌕ Search

Biomedical subjects

R Verhoef

Publications and source records attributed to R Verhoef.

At least 19 recordsLinked to original sources
PubMed2006

Colanic acid is an exopolysaccharide common to many enterobacteria isolated from paper-machine slimes.

In this study, polysaccharide-producing bacteria were isolated from slimes collected from two Finnish and one Spanish paper mill and the exopolysaccharides (EPSs) produced by 18 isolates were characterised. Most of the isolates, selected on the bases of slimy colony morphology, were members of the family Enterobacteriaceae most frequently belonging to the genera Enterobacter and Klebsiella including Raoultella. All of the EPSs analysed showed the presence of charged groups in the form of uronic acid or pyruvate revealing the polyanionic nature of these polysaccharides. Further results of the carbohydrate analysis showed that the EPS produced by nine of the enterobacteria was colanic acid.

Biofilms↗
PubMed2004

Physico-chemical and transglucosylation properties of recombinant sucrose phosphorylase from Bifidobacterium adolescentis DSM20083.

Clones of a genomic library of Bifidobacterium adolescentis were grown in minimal medium with sucrose as sole carbon source. An enzymatic fructose dehydrogenase assay was used to identify sucrose-degrading enzymes. Plasmids were isolated from the positive colonies and sequence analysis revealed that two types of insert were present, which only differed with respect to their orientation in the plasmid. An open reading frame of 1,515 nucleotides with high homology for sucrose phosphorylases was detected on these inserts. The gene was designated SucP and encoded a protein of 56,189 Da. SucP was heterologously expressed in Escherichia coli, purified, and characterized. The molecular mass of SucP was 58 kDa, as estimated by SDS-PAGE, while 129 kDa was found with gel permeation, suggesting that the native enzyme was a dimer. The enzyme showed high activity towards sucrose and a lower extent towards alpha-glucose-1-phosphate. The transglucosylation properties were investigated using a broad range of monomeric sugars as acceptor substrate for the recombinant enzyme, while alpha-glucose-1-phosphate served as donor. D- and L-arabinose, D- and L-arabitol, and xylitol showed the highest production of transglucosylation products. The investigated disaccharides and trisaccharides were not suitable as acceptors. The structure of the transglucosylation product obtained with D-arabinose as acceptor was elucidated by NMR. The structure of the synthesized non-reducing dimer was alpha-Glcp(1-->1)beta-Araf.

Bifidobacterium↗
PubMed1987

Population registers and population statistics.

The authors examine the use of population registers in the production of demographic statistics. "To do this, we first describe these registers; we then examine their further development as an independent source of population statistics--including current population estimates, vital and migration statistics--and as an alternative to population censuses. In conclusion, we consider a number of essential features of registers, including the original collection of data, the system's lifetime, privacy protection, and the government's ability to bring about a balance among conflicting interests regarding the collection and use of the data." The discussion is illustrated using examples from the Netherlands and Denmark.

Censuses↗
PubMed1986

Aliens in the Netherlands on January 1st 1985.

"The increase in the number of aliens in the Netherlands has slowed down considerably since 1980. Nevertheless, we can still speak of significant changes in the alien population. This article gives a brief description of these changes in 1984 and looks at differences with the recent past.... Some preliminary figures on changes in the alien population in the first half of 1985 are also given. The article concludes with a summary of the (annually) available figures on aliens in the Netherlands." Data are included on people born in Suriname or the Netherlands Antilles who have Dutch nationality.

Americas↗