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Biomedical subjects

Arie van der Ende

Publications and source records attributed to Arie van der Ende.

18 recordsLinked to original sources
PubMed2007

Procoagulant and fibrinolytic activity in cerebrospinal fluid from adults with bacterial meningitis.

OBJECTIVES: This study investigated levels of coagulation and fibrinolysis factors in cerebrospinal fluid (CSF) from adults with bacterial meningitis in relation to development of brain infarction. METHODS: CSF was collected from 92 adults with community-acquired bacterial meningitis, who participated in the prospective Dutch Meningitis Cohort Study; 8 patients with viral meningitis and 9 healthy control subjects. Levels of proteins involved in the coagulation cascade were determined by means of immunoassays. RESULTS: Bacterial meningitis was accompanied by local activation of coagulation, as shown by significantly higher CSF soluble tissue factor (P<0.001) and prothrombin fragment F1+2 concentrations (P<0.001) as compared to viral meningitis patients and controls. This was accompanied by a significantly higher D-dimer formation (P<0.001). In addition, in bacterial meningitis fibrinolysis was attenuated, since CSF plasminogen activator inhibitor (PAI)-1 levels were significantly higher as compared to the controls (P=0.02). In patients with bacterial meningitis who developed brain infarction, CSF PAI-1 levels were higher than in those without infarction (P=0.04). CONCLUSIONS: Activation of coagulation and attenuation of fibrinolysis in the CSF are important features of bacterial meningitis; the net effect on fibrin turnover may contribute to the development of brain infarction.

Adolescent↗
PubMed2006

Soluble triggering receptor expressed on myeloid cells 1: a biomarker for bacterial meningitis.

OBJECTIVE: To evaluate whether soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) in CSF can serve as a biomarker for the presence of bacterial meningitis and outcome in patients with this disease. DESIGN: Retrospective study of diagnostic accuracy. SETTING AND PATIENTS: CSF was collected from 92 adults with community-acquired bacterial meningitis who participated in the prospective Dutch Meningitis Cohort Study; 8 patients with viral meningitis and 9 healthy control subjects. RESULTS: CSF sTREM-1 levels were higher in patients with bacterial meningitis (median 82 pg/ml, range 0-988) than in those with viral meningitis (0 pg/ml, 0-48) and controls (0 pg/ml, 0-36). The diagnostic accuracy of sTREM-1 in discriminating between patients with and without bacterial meningitis, expressed as the area under the receiver operating characteristic curve, was 0.82. At a cutoff level of 20 pg/ml the sensitivity was 0.73 and specificity 0.77. In patients with bacterial meningitis CSF sTREM-1 levels were associated with mortality (survivors, median 73 pg/ml, range 0-449 pg/ml; nonsurvivors, 15 pg/ml, 0-988). CONCLUSIONS: Measuring sTREM-1 in CSF may be a valuable new additional approach to accurately diagnose bacterial meningitis and identify patients at high risk for adverse outcome. Therefore a prospective study of sTREM-1 as a biomarker in bacterial meningitis is needed.

Biomarkers↗
PubMed2006

Compositional discordance between prokaryotic plasmids and host chromosomes.

BACKGROUND: Most plasmids depend on the host replication machinery and possess partitioning genes. These properties confine plasmids to a limited range of hosts, yielding a close and presumably stable relationship between plasmid and host. Hence, it is anticipated that due to amelioration the dinucleotide composition of plasmids is similar to that of the genome of their hosts. However, plasmids are also thought to play a major role in horizontal gene transfer and thus are frequently exchanged between hosts, suggesting dinucleotide composition dissimilarity between plasmid and host genome. We compared the dinucleotide composition of a large collection of plasmids with that of their host genomes to shed more light on this enigma. RESULTS: The dinucleotide frequency, coined the genome signature, facilitates the identification of putative horizontally transferred DNA in complete genome sequences, since it was found to be typical for a certain genome, and similar between related species. By comparison of the genome signature of 230 plasmid sequences with that of the genome of each respective host, we found that in general the genome signature of plasmids is dissimilar from that of their host genome. CONCLUSION: Our results show that the genome signature of plasmids does not resemble that of their host genome. This indicates either absence of amelioration or a less stable relationship between plasmids and their host. We propose an indiscriminate lifestyle for plasmids preserving the genome signature discordance between these episomes and host chromosomes.

Base Composition↗
PubMed2006

Identification of acquired DNA in Neisseria lactamica.

Anomalous DNA (aDNA) in prokaryotic genomes, identified by its aberrant nucleotide composition, generally represents horizontally acquired DNA. Previous studies showed that frequent DNA transfer occurs between commensal Neisseriae and Neisseria meningitidis. Currently, it is unknown whether aDNA regions are also transferred between these species. The genome of Neisseria lactamica strain 892586 was assessed by a strategy that enables the selective isolation of aDNA, using endonucleases with recognition sites that are overrepresented in aDNA. Of eight regions with aDNA, five displayed similarity to virulence-associated meningococcal sequences. Of three aDNA fragments with limited or no similarity to neisserial sequences, one encodes a novel putative autotransporter/adhesin. The remaining two fragments are adjacent in the N. lactamica genome, and encode a novel putative ATPase/subtilisin-like protease operon. A similar operon is present in the genomes of different respiratory tract pathogens. The identification of aDNA from N. lactamica with similarity to meningococcal aDNA shows that genetic exchange between the Neisseriae is not limited to the neisserial core genome. The discovery of aDNA in N. lactamica similar to a locus in other pathogens substantially expands the neisserial gene pool.

Adenosine Triphosphatases↗
PubMed2006

Of microbe and man: determinants of Helicobacter pylori-related diseases.

The human gastric pathogen Helicobacterpylori infects the human gastric mucus layer of approximately half of the world's population. Colonization with this bacterium results in superficial gastritis without clinical symptoms, but can progress into gastric or duodenal ulcers, gastric malignancies and mucosa-associated lymphoid tissue-lymphomas. Disease outcome is affected by a complex interplay between host, environmental and bacterial factors. Irrespective of disease outcome, the majority of H. pylori infected individuals remain colonized for life. Changing conditions in the human gastric mucosa may alter gene expression and/or result in the outgrowth of more fit H. pylori variants. As such, H. pylori is a highly flexible organism that is optimally adapted to its host. the heterogeneity in H. pylori populations make predictions on H. pylori-related pathogenesis difficult. In this review, we discuss host, environmental and bacterial factors that are important in disease progression. Moreover, H. pylori adaptive mechanisms, which allow its life-long survival and growth in the gastric mucosa are considered.

Adaptation, Physiological↗
PubMed2006

Plasmid diversity in neisseriae.

Horizontal gene transfer constitutes an important force in prokaryotic genome evolution, and it is well-known that plasmids are vehicles for DNA transfer. Chromosomal DNA is frequently exchanged between pathogenic and commensal neisseriae, but relatively little is known about plasmid diversity and prevalence among these nasopharyngeal inhabitants. We investigated the plasmid contents of 18 Neisseria lactamica isolates and 20 nasopharyngeal Neisseria meningitidis isolates. Of 18 N. lactamica strains, 9 harbored one or more plasmids, whereas only one N. meningitidis isolate contained a plasmid. Twelve plasmids were completely sequenced, while five plasmid sequences from the public databases were also included in the analyses. On the basis of nucleic acid sequences, mobilization, and replicase protein alignments, we distinguish six different plasmid groups (I to VI). Three plasmids from N. lactamica appeared to be highly similar on the nucleotide level to the meningococcal plasmids pJS-A (>99%) and pJS-B (>75%). The genetic organizations of two plasmids show a striking resemblance with that of the recently identified meningococcal disease-associated (MDA) phage, while four putative proteins encoded by these plasmids show 25% to 39% protein identity to those encoded by the MDA phage. The putative promoter of the gene encoding the replicase on these plasmids contains a polycytidine tract, suggesting that replication is subjected to phase variation. In conclusion, extensive plasmid diversity is encountered among commensal neisseriae. Members of three plasmid groups are found in both pathogenic and commensal neisseriae, indicating plasmid exchange between these species. Resemblance between plasmids and MDA phage may be indicative of dissemination of phage-related sequences among pathogenic and commensal neisseriae.

Bacterial Proteins↗
PubMed2006

Multiple-locus variable-number tandem repeat analysis of Neisseria meningitidis yields groupings similar to those obtained by multilocus sequence typing.

We identified many variable-number tandem repeat (VNTR) loci in the genomes of Neisseria meningitidis serogroups A, B, and C and utilized a number of these loci to develop a multiple-locus variable-number tandem repeat analysis (MLVA). Eighty-five N. meningitidis serogroup B and C isolates obtained from Dutch patients with invasive meningococcal disease and seven reference strains were analyzed using MLVA and multilocus sequence typing (MLST). MLVA, based on eight VNTR loci with limited variability in the number of repeats, yielded clustering of the strains similar to that obtained by MLST, with congruence between both methods amounting to 69%. The ability to recognize clonal complexes makes MLVA a valuable high-throughput method to serve as a tool complementary to MLST. Four highly variable VNTR loci were used in a second assay to analyze N. meningitidis serogroup C strains collected during an outbreak of meningococcal disease in The Netherlands. Typing based on the latter VNTR loci enabled differentiation of isolates with identical MLST sequence types and grouped epidemiologically related strains.

Bacterial Typing Techniques↗
PubMed2005

A Helicobacter pylori TolC efflux pump confers resistance to metronidazole.

In Helicobacter pylori, the contribution of efflux proteins to antibiotic resistance is not well established. As translocases that act in parallel may have overlapping substrate specificities, the loss of function of one such translocase may be compensated for by that of another translocase with no effect on susceptibilities to antibiotics. The genome of H. pylori 26695 was assessed for the presence of putative translocases and outer membrane efflux or TolC-like proteins which could interact to form efflux systems involved in drug resistance. Twenty-seven translocases were identified, of which HP1184 was the sole representative of the multidrug and toxic compound extrusion family of translocases and which could thus have a unique substrate specificity. In addition, four TolC-like proteins (HP0605, HP0971, HP1327, and HP1489) were identified. Thus, it is feasible that inactivation of a TolC-like protein would affect the functions of multiple translocases. We aimed to determine whether efflux systems contribute to antimicrobial susceptibility by evaluation of the susceptibility profiles of an HP1184-knockout mutant, four mutants in which one of the four TolC homologs was inactivated, as well as a mutant in which both HP0605 and HP0971 were inactivated. The HP1184- and HP1489-knockout mutants both showed increased susceptibilities to ethidium bromide, while the HP0605-knockout mutant exhibited increased susceptibilities to novobiocin and sodium deoxycholate. The HP0605 and HP0971 double-knockout mutant was also more susceptible to metronidazole, in addition to being susceptible to novobiocin and sodium deoxycholate. Thus, active efflux is an eminent means of resistance to antimicrobials in H. pylori and resembles the situation in other bacteria.

Anti-Bacterial Agents↗
PubMed2005

The N5-glutamine S-adenosyl-L-methionine-dependent methyltransferase PrmC/HemK in Chlamydia trachomatis methylates class 1 release factors.

The gene prmC, encoding the putative S-adenosyl-L-methionine (AdoMet)-dependent methyltransferase (MTase) of release factors (RFs) of the obligate intracellular pathogen Chlamydia trachomatis, was functionally analyzed. Chlamydial PrmC expression suppresses the growth defect of a prmC knockout strain of Escherichia coli K-12, suggesting an interaction of chlamydial PrmC with E. coli RFs in vivo. In vivo methylation assays carried out with recombinant PrmC and RFs of chlamydial origin demonstrated that PrmC methylates RFs within the tryptic fragment containing the universally conserved sequence motif Gly-Gly-Gln. This is consistent with the enzymatic properties of PrmC of E. coli origin. We conclude that C. trachomatis PrmC functions as an N5-glutamine AdoMet-dependent MTase, involved in methylation of RFs.

Amino Acid Motifs↗
PubMed2005

Interrelationship between polymorphisms of incA, fusogenic properties of Chlamydia trachomatis strains, and clinical manifestations in patients in The Netherlands.

IncA variation among Dutch Chlamydia trachomatis isolates was investigated. Of 98 strains, two carried an incA with a premature stop codon, lacked IncA, and were nonfusogenic, while 96 contained an intact incA, expressed IncA, and were fusogenic. Among these 96 strains, nine IncA sequence types were found, of which the three most frequently encountered (88% of the strains) were randomly distributed among symptomatic and asymptomatic patients.

Bacterial Proteins↗
PubMed2005

Increase in genetic diversity of Haemophilus influenzae serotype b (Hib) strains after introduction of Hib vaccination in The Netherlands.

Recently, there has been an increase in The Netherlands in the number of cases of invasive disease caused by Haemophilus influenzae serotype b (Hib). To study a possible change in the Hib population that could explain the rise in incidence, a multiple-locus variable number tandem repeats analysis (MLVA) was developed to genotype H. influenzae isolates. The MLVA enabled the differentiation of H. influenzae serotype b strains with higher discriminatory power than multilocus sequence typing (MLST). MLVA profiles of noncapsulated H. influenzae and H. influenzae serotype f strains were more heterogeneous than serotype b strains and were distinct from Hib, although some overlap occurred. The MLVA was used to genotype a collection of 520 H. influenzae serotype b strains isolated from patients in The Netherlands with invasive disease. The strains were collected from 1983 from 2002, covering a time period of 10 years before and 9 years after the introduction of the Hib vaccine in the Dutch national vaccination program. MLVA revealed a sharp increase in genetic diversity of Hib strains isolated from neonates to 4-year-old patients after 1993, when the Hib vaccine was introduced. Hib strains isolated from patients older than 4 years in age were genetically diverse, and no significant change in diversity was seen after the introduction of the vaccine. These observations suggest that after the introduction of the Hib vaccine young children no longer constitute the reservoir for Hib and that they are infected by adults carrying genetically diverse Hib strains.

Adult↗
PubMed2005

Increased attack rate of meningococcal disease in children with a pregnant mother.

OBJECTIVE: To investigate the relationship between meningococcal disease and family composition, especially pregnancy in mothers. METHODS: This was a retrospective matched case-control study. Case patients were children (aged 0-18 years) who had meningococcal disease and were admitted to our hospital from 1990 to 2002. Children who were admitted to 1 of the general pediatric wards of the hospital during the same period and did not have meningococcal disease served as control subjects. One control subject (matched according to gender, age, and year, and season of admission) was enrolled for each case patient. Parents of case patients and control subjects were asked to fill out a questionnaire on family composition, birth dates of siblings, and pregnancy at the time of hospital admission. RESULTS: A total of 88 matched case-control pairs were included. In the case group, 17 (19%) mothers reported having been pregnant at the time of hospitalization of their child, compared with 2 (2%) in the control group. Other family characteristics were not different. After adjustment for confounding factors, pregnancy of mothers remained a significant risk factor for meningococcal disease in children (odds ratio: 11.7; 95% confidence interval: 2.6-53.9). CONCLUSIONS: Meningococcal disease in children was highly associated with pregnancy of the patient's mother during hospitalization. Mechanisms by which the presence of a pregnant mother in a family affects the attack rate of meningococcal disease in her children need additional investigation.

Adolescent↗
PubMed2004

Helicobacter pylori HP1034 (ylxH) is required for motility.

BACKGROUND: Helicobacter pylori motility is essential for the colonization and persistence in the human gastric mucosa. So far, more than 50 genes have been described to play a role in flagellar biosynthesis. H. pylori YlxH (HP1034) is annotated as an ATP-binding protein. However, H. pylori YlxH shows similarity to proteins involved in the flagellar biosynthesis of other bacterial species. Moreover, H. pylori ylxH is found adjacent to genes involved in flagellar biosynthesis in the sequenced genomes of H. pylori 26695 and J99. We therefore aimed to determine the role of YlxH in H. pylori motility. MATERIALS AND METHODS: Motility, flagellar biosynthesis and transcriptional regulation of genes encoding flagellar proteins was compared between H. pylori 11A and a knockout of ylxH in H. pylori 11A. RESULTS: The ylxH knockout in H. pylori 11A was nonmotile on soft agar plates, whereas H. pylori 11A was motile. Furthermore, the H. pylori 11A ylxH knockout lacked flagella, while H. pylori 11A possessed two to three flagella. Transcription of H. pylori flaG (HP0751), fliM (HP1031) and fliA (HP1032) was reduced in the H. pylori 11A ylxH(;) knockout, whereas transcription of flaA (HP0601) was not altered. However, Western blot analysis showed substantially reduced amounts of the major flagellin subunit FlaA in the H. pylori 11A ylxH knockout compared to H. pylori 11A. CONCLUSIONS: H. pylori YlxH is essential for the assembly of flagella and hence for the motility of H. pylori.

Amino Acid Sequence↗
PubMed2004

Nutrients released by gastric epithelial cells enhance Helicobacter pylori growth.

BACKGROUND: Helicobacter pylori survives and proliferates in the human gastric mucosa. In this niche, H. pylori adheres to the gastric epithelial cells near the tight junctions. In vitro, H. pylori proliferated well in tissue-culture medium near gastric epithelial cells. However, in the absence of epithelial cells, growth of H. pylori could only be established in tissue-culture medium when, prior to the experiment, it was preincubated near gastric epithelial cells. Therefore, we aimed to determine whether diffusion of nutrients derived from epithelial cells was required for H. pylori growth in Dulbecco's modified Eagle's minimal essential medium (DMEM) cell culture medium. MATERIALS AND METHODS: Cell culture conditions essential for H. pylori growth in vitro were determined with gastric epithelial HM02 cells. RESULTS: Deprivation of iron in cell-culture-conditioned DMEM resulted in a growth arrest of H. pylori. However, near gastric epithelial cells, growth of H. pylori was resistant to iron deprivation. Evidently, when residing close to epithelial cells, H. pylori was able to fulfil its iron requirements, even when the DMEM was deprived of iron. Nevertheless, supplementation with iron alone did not restore H. pylori growth in DMEM, hence other nutrients were deficient as well in the absence of epithelial cells. Growth of H. pylori in DMEM was restored when hypoxanthine, L-alanine and L-proline were added to the DMEM. CONCLUSIONS: Diffusion of (precursors of) these nutrients from the gastric epithelial cells is essential for H. pylori growth in vitro. We hypothesize that in vivo, H. pylori favors colonization near the tight junctions, to gain maximal access to the nutrient(s) released by gastric epithelial cells.

Alanine↗
PubMed2003

Induced Helicobacter pylori vacuolating cytotoxin VacA expression after initial colonisation of human gastric epithelial cells.

To study the effect of initial colonisation on Helicobacter pylori gene expression, altered H. pylori gene transcription during co-culture with human gastric epithelial cells was determined. Therefore, an insertion library of H. pylori with random chromosomal fusions to a promoterless cat gene was grown in the presence of HM02 gastric epithelial cells and varying levels of chloramphenicol. One H. pylori transformant was chloramphenicol-resistant in the presence, but chloramphenicol-susceptible in the absence of gastric epithelial HM02 cells. This transformant had the promoterless cat gene inserted into the HP0887 gene, which encodes the vacuolating cytotoxin VacA, an important virulence factor of H. pylori. Reverse transcriptase polymerase chain reaction on cDNA of this transformant confirmed vacA upregulation near HM02 cells. These results show the applicability of this technique to study H. pylori gene regulation in its natural environment.

Bacterial Proteins↗
PubMed2003

Assessment of Chlamydia trachomatis infection of semen specimens by ligase chain reaction.

Diagnostic potential of the Chlamydia trachomatis ligase chain reaction system (LCx) to assess the presence of C. trachomatis in urine and semen specimens was evaluated. Paired urine and semen specimens from 153 asymptomatic male partners of subfertile couples attending our Center for Reproductive Medicine were examined by LCx. As controls, 19 semen samples from four donors who were participating in the programme for artificial insemination were used. Of these, 12 samples had previously been shown to be C. trachomatis-positive by an in-house PCR. C. trachomatis was detected by LCx in seven of 153 (5 %) urine samples. None of the 153 semen samples tested positive by LCx. Also, none of the 12 C. trachomatis-containing control semen samples were positive by LCx. By in-house PCR, seven urine specimens and two of 153 (1 %) semen samples tested positive. The corresponding urine samples of these male partners were also C. trachomatis-positive, as well as the 12 C. trachomatis-containing samples from donors. In conclusion, LCx is not sensitive enough to assess the presence of C. trachomatis in semen specimens; therefore, this method is not recommended to routinely screen semen specimens from donors who participate in programmes for artificial insemination or male partners of subfertile couples for C. trachomatis.

Chlamydia Infections↗
PubMed2002

Assessment of clarithromycin-resistant Helicobacter pylori among patients in Shanghai and Guangzhou, China, by primer-mismatch PCR.

Of 96 Helicobacter pylori isolates from patients in Shanghai and Guangzhou, China, 5 had the A2143G 23S rRNA mutation as determined by primer-mismatch PCR and were resistant to clarithromycin by the E-test. The remaining isolates were primer-mismatch PCR negative and susceptible to clarithromycin. The conclusion is that the prevalence of clarithromycin-resistant H. pylori isolates among these Chinese patients is 5%.

Anti-Bacterial Agents↗