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Biomedical subjects

J Jansen

Publications and source records attributed to J Jansen.

At least 19 recordsLinked to original sources
PubMed2006

Genetic distance sampling: a novel sampling method for obtaining core collections using genetic distances with an application to cultivated lettuce.

This paper introduces a novel sampling method for obtaining core collections, entitled genetic distance sampling. The method incorporates information about distances between individual accessions into a random sampling procedure. A basic feature of the method is that automatically larger samples are obtained if accessions are further apart and smaller samples if accessions are closer together. Genetic distance sampling can be used in conjunction with predefined stratifications of the accessions. Sample sizes are determined automatically; they depend on the distances between accessions within strata. The method is applied to the collection of cultivated lettuce of the Centre for Genetic Resources, the Netherlands. In this paper, genetic distances between accessions are obtained using AFLP marker data. However, genetic distance sampling can be applied using any measure of genetic distance between accessions. Some properties of genetic distance sampling are discussed.

Agriculture↗
PubMed2006

Hemicrania with massive autonomic manifestations and circumscribed eyelid erythema.

OBJECTIVES: To describe a unilateral headache that in addition to the typical shortlasting unilateral neuralgiform headache attacks with conjunctival injection, tearing, sweating and rhinorrhea (SUNCT) syndrome - traits with excessive and ipsilateral autonomic phenomena - had circumscribed eyelid erythema and adjacent ocular redness. OBSERVATIONS: A 60-year-old female had excessive, right-sided lacrimation and local pain at 15 years of age. Due to steadily increasing discomfort, with lacrimation and swelling over the outer part of the upper eyelid, the right lacrimal gland was removed at 20 years of age, with a suspicion of lacrimal gland adenoma. Preoperatively, symptomatic side mild-degree eyelid erythema/rhinorrhea were integral parts of the attack. After years with minor complaints, she, in the mid-twenties, experienced more long-lasting pain attacks, and pain soon became the main problem. A marked, distinct erythema on the lateral part of the right-sided eyelids and marked, localized 'eye redness' in the adjacent area were main ingredients of the attacks together with eyelid edema and viscous rhinorrhea. There were visible vessels below the eye, and telangiectasia of the upper eyelid. CONCLUSIONS: This headache has many similarities with SUNCT - but has several, grossly deviating traits: the temporal aspects, excruciatingly intense pain attacks, and above all marked, lateral eye-lid erythema, and adjacent, massive ocular reddening. This constellation probably alienates it from SUNCT.

Anticonvulsants↗
PubMed2005

A note on the measurement of genetic diversity within genebank accessions of lettuce (Lactuca sativa L.) using AFLP markers.

This paper discusses a statistical approach for measuring genetic diversity within genebank accessions of a self-fertilising species. This approach is applied to lettuce (Lactuca sativa L.), using AFLP marker data on a set of 1,390 accessions, representing six different lettuce types. Knowledge of the within-accession genetic diversity is important for decisions about the way accessions have to be maintained by genebanks. It is argued that if the within-accession diversity is small, as can be expected for a self-fertilising species like L. sativa, the best approach is to sample as many accessions as possible with only two plants per accession and estimate the within-accession diversity by the proportion of accessions of which the individuals are different.

DNA, Plant↗
PubMed2005

Decreased cellular uptake and metabolism in Allan-Herndon-Dudley syndrome (AHDS) due to a novel mutation in the MCT8 thyroid hormone transporter.

We report a novel 1 bp deletion (c.1834delC) in the MCT8 gene in a large Brazilian family with Allan-Herndon-Dudley syndrome (AHDS), an X linked condition characterised by severe mental retardation and neurological dysfunction. The c.1834delC segregates with the disease in this family and it was not present in 100 control chromosomes, further confirming its pathogenicity. This mutation causes a frameshift and the inclusion of 64 additional amino acids in the C-terminal region of the protein. Pathogenic mutations in the MCT8 gene, which encodes a thyroid hormone transporter, results in elevated serum triiodothyronine (T3) levels, which were confirmed in four affected males of this family, while normal levels were found among obligate carriers. Through in vitro functional assays, we showed that this mutation decreases cellular T3 uptake and intracellular T3 metabolism. Therefore, the severe neurological defects present in the patients are due not only to deficiency of intracellular T3, but also to altered metabolism of T3 in central neurones. In addition, the severe muscle hypoplasia observed in most AHDS patients may be a consequence of high serum T3 levels.

Adult↗
PubMed2005

Construction of linkage maps in full-sib families of diploid outbreeding species by minimizing the number of recombinations in hidden inheritance vectors.

This article investigates the construction of linkage maps by means of the reconstruction of hidden inheritance vectors. An inheritance vector provides a description of the origin of marker alleles in an individual in terms of a binary code indicating the grandparental origin of the alleles. The practical application that is considered is the full-sib family of a diploid outbreeding species. Essentially, map construction is considered as an optimization problem in which marker data are used as restrictions on hidden inheritance vectors. Simulated annealing, a form of combinatorial optimization, is used to minimize the number of recombinations between adjacent markers. The new algorithm is applied to simulated data as well as to practical data obtained from a cross between two apple cultivars. For the practical data, a detailed procedure for examining the reliability of individual markers and their positions on the map is presented. Extensions of the method for more complicated population structures are discussed.

Algorithms↗
PubMed2005

Lifestyle-related risks: are trends in Europe converging?

OBJECTIVES: What has become of lifestyle differences in a united Europe, where member states become more and more similar on aspects such as welfare systems and population dynamics? In this paper, we try to answer the question whether the gap in lifestyle-related risk factors in Europe has narrowed over the past 30-40 years. METHODS: Smoking, alcohol consumption, physical activity, obesity and food consumption all have an impact on cancer, cardiovascular disease and other non-communicable diseases. Databases of Eurostat, OECD (Organisation for Economic Co-operation and Development) and the World Health Organisation were screened for data on lifestyle-related risk factors in the European Union, and a literature search was performed for studies that collected international comparable data about the selected factors. RESULTS: The gap in European lifestyle has narrowed over the past 30-40 years for smoking (women), alcohol consumption and total fat intake. For fruit and vegetable consumption, convergence is not occurring. For some risk factors, such as smoking and obesity, intranational differences surpass the international differences. CONCLUSIONS: The results support the notion of convergent lifestyles among Europeans over time. We also found that there is a serious lack of reliable data on lifestyle-related risk factors that are suitable for international comparison. It is essential to invest in reliable and internationally comparable data, obtained according to best evidence, to get more insight into real differences regarding risk factors in Europe. The European Public Health programme may be an opportunity to realize these goals.

Age Factors↗
PubMed2005

Mutation scanning of the p53 tumor suppressor gene in renal and liver transplant patients in Hungary.

INTRODUCTION: The increased incidence of malignancies among transplanted patients is well known. Abnormal function of the p53 tumor suppressor gene has been reported in more than half of all tumors. The aim of our study was to detect point mutations of p53 gene in transplanted patients because the presence of mutations may be a predictive factor for tumor development. An earlier diagnosis can help to develop new strategies for immunosuppressive therapies. METHODS: Three point mutations were chosen based on the literature: exon5-codon175, exon7-codon248, exon8-codon273. Genomic DNA from the plasma of 60 liver, 362 renal transplants, and 45 nontransplanted patients with different tumors and 20 suspected healthy patients were analyzed with a real-time PCR method using the Roche LightCycler. The mutations were evaluated by melting curve analysis. RESULTS: We elaborated a special protocol for scanning the above mentioned p53 point mutations, which were proved by sequencing as well. Among 487 patients, 486 showed a wild-type genotype. The only patient carrying a mutation at codon 273 (heterozygous) was a liver transplant patient, who developed pancreas carcinoma and had already died. CONCLUSION: Our data suggest that mutations of the targeted codons in leukocyte DNA seem to be rare, but a mutation could be lethal. The evaluated three point mutations of p53 gene were not predictive for tumor development.

Base Sequence↗
PubMed2005

Thyroid hormone transporters.

Thyroid hormone is important for development of various tissues, in particular brain, and for regulation of metabolic processes throughout life. The follicular cells of the thyroid gland produce predominantly T4 (thyroxine), but the biological activity of thyroid hormone is largely exerted by T3 (3,3',5-tri-iodothyronine). The deiodinases involved in T4-to-T3 conversion or T4 and T3 degradation, as well as the T3 receptors, are located intracellularly. Therefore the action and metabolism of thyroid hormone require transport of iodothyronines across the cell membrane via specific transporters. Recently, a number of transporters capable of cellular uptake of iodothyronines have been identified. The most specific transporters identified so far are OATP1C1 and MCT8, which appear to be involved in T4 transport across the blood-brain barrier, and in T3 transport into brain neurons, respectively. The MCT8 gene is located on human chromosome Xq13, and mutations in MCT8 are associated with X-linked severe psychomotor retardation and elevated serum T3 levels.

Amino Acid Transport Systems↗
PubMed2005

Genetic diversity in perennial ryegrass and white clover among old Dutch grasslands as compared to cultivars and nature reserves.

To support conservation policies for old Dutch grasslands that are still in agricultural use, morphological variation and AFLP-based (amplified fragment length polymorphism-based) genetic diversity was studied in perennial ryegrass and white clover populations and compared with the diversity in reference varieties. In addition, AFLP variation was also studied in grasslands located in nature reserves. From principal component analysis (PCA), it appeared that date of ear emergence in perennial ryegrass and characters related to plant vigour in white clover were the main morphological characters separating the reference varieties from the old Dutch grassland populations, and some of the grassland populations from each other. In both species, intrapopulation variation was lower for the reference varieties. Lower heterogeneity within the reference varieties was also found in the AFLP analysis. All common AFLP's observed in old Dutch grasslands could also be found in the reference varieties and nature reserves. Only a small number of low-frequency alleles found in old Dutch grasslands were absent from the other two groups. However, band frequencies of markers could vary considerably between populations, which may have been caused by selection. Analysis of the AFLP data by PCA distinguished the majority of reference varieties from the old Dutch grasslands, and showed genetic differentiation only between some grasslands. Comparison of old Dutch grasslands with grasslands in nature reserves indicated that basically the same range of genetic variation is covered by the two groups. Our study indicates that the Netherlands harbour a more or less continuous population for major parts of the diversity of perennial ryegrass and white clover. It was concluded that no specific conservation measures are presently needed to maintain genetic diversity of perennial ryegrass and white clover occurring in old Dutch grasslands.

Biodiversity↗
PubMed2004

The effect of inelastic scattering on crystal structure refinement from electron diffraction patterns recorded under almost parallel illumination.

Recently a number of crystal structures were determined using electron diffraction data with an almost parallel electron beam. In many cases no energy filtering was applied. On the other hand, the contrast in convergent beam electron diffraction patterns is greatly improved by energy filtering of the electrons. To investigate whether energy filtering will improve the accuracy of the structure analysis from diffraction data recorded under an almost parallel beam condition, we recorded diffraction patterns of the [100] zone of YBa(2)Cu(3)O(7) using unfiltered electrons, zero-loss electrons and plasmon-loss electrons, respectively. Subsequently, the structure is refined based on these different electron diffraction datasets, using the program MSLS (Acta Crystallogr. A 54 (1998) 91). The results show that the obtained atomic positions are not significantly different for the chosen filter conditions. Even with amorphous carbon deposited on the specimen, which will cause a significant increase (>40 times) of energy-loss electrons, the structure refinement led to the same atomic positions.

Journal Article↗
PubMed2004

Impaired PBPC collection in patients with myeloma after high-dose melphalan.

BACKGROUND: Tandem stem cell transplantation is an important treatment option for patients with myeloma and some additional tumors. In an attempt to reduce the contamination of the stem cell graft with tumor cells, patients with myeloma who entered complete remission after the first transplant underwent a second episode of mobilization to obtain progenitor cells for the second transplant. METHODS: Twenty-two patients with myeloma participated in the study. The first mobilization utilized CY, etoposide and filgrastim. The second mobilization used the same regimen, but seven patients received only filgrastim. The interval between the two collection periods was 6 months (median; range 4-9 months). The preparative regimen for the first transplant consisted of melphalan 200 mg/m(2). RESULTS: The number of total white cells collected during the two collection episodes was similar: 10.8+/-1.6 x 10(8)/kg white cells vs. 11.8+/-1.7 x 10(8)/kg white cells (P=0.63). The collected CD34(+) cell dose was much larger during the first collection: 45.2+/-8.4 x 10(6)/kg vs. 6.9+/-2.7 x 10(6)/kg (P<0.001). Similarly, the collected colony-forming unit (CFU)-GM dose was much larger during the first collection: 295.4+/-59.3 x 10(4)/kg vs. 67.3+/-21.6x10(4)/kg (P<0.001). While the CD34(+) cells collected during the two collection episodes correlated significantly (r=0.55, P<0.01); the first dose was a median of 14.9-fold larger. DISCUSSION: No laboratory parameter was able reliably to predict the results of the second collection. A second mobilization/collection episode as part of a tandem transplant approach carries a considerable risk of failing to obtain sufficient progenitor cells.

Adult↗
PubMed2004

Emerging food-borne zoonoses.

Diarrhoeal diseases, almost all of which are caused by food-borne or waterborne microbial pathogens, are leading causes of illness and death in less developed countries, killing an estimated 1.9 million people annually at the global level. Even in developed countries, it is estimated that up to one third of the population are affected by microbiological food-borne diseases each year. The majority of the pathogens causing this significant disease burden are now considered to be zoonotic. The occurrence of some of these zoonotic pathogens seems to have increased significantly over recent years. The factors involved in such increases have not been well studied, but they are generally agreed to include changes in animal production systems and in the food production chain. Both types of changes can cause corresponding changes in patterns of exposure to the pathogens and the susceptibility pattern of the human population. This paper will not attempt a more in-depth analysis of such factors. The authors briefly describe five of the most important emerging food-borne zoonotic pathogens: Salmonella spp., Campylobacter spp., enterohaemorrhagic Escherichia coli, Toxoplasma gondii and Cryptosporidium parvum. The paper does not include a full description of all important emerging food-borne pathogens but instead provides a description of the present situation, as regards these globally more important pathogens. In addition, the authors describe each pathogen according to the new framework of a Food and Agriculture Organization (FAO)/World Health Organization (WHO) microbiological risk assessment, which consists of hazard identification and characterisation, exposure assessment and risk characterisation. Moreover, the authors provide a brief account of attempts at risk mitigation, as well as suggestions for risk management for some of these pathogens, based on thorough international FAO/WHO risk assessments. The authors emphasise the importance of science-based programmes for the continued reduction of pathogens at relevant points of the 'farm-to-fork' food production chain, as this is the only sustainable basis for further reducing risks to human health in the area of preventable food-borne diseases.

Animal Husbandry↗
PubMed2003

Electrostatic spray deposition (ESD) of calcium phosphate coatings.

Using electrostatic spray deposition (ESD), thin calcium phosphate layers were deposited onto commercially pure cp-Ti substrates. ESD is a thin-film technique that enables the deposition of inorganic thin films onto metallic substrates using a simple and cheap experimental set-up. The results show that coating structure and morphology can be tailored by choosing the appropriate combination of deposition parameters. Scanning electron microscopy revealed that various surface morphologies, ranging from dense to very porous coatings, can be obtained. Particularly interesting was a unique reticular coating morphology characterized by a three-dimensionally interconnected pore network. X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FTIR) analyses showed that crystalline carbonate apatite coatings were formed after heat treatment of as-deposited ESD coatings.

Apatites↗
PubMed2002

Determination of absolute configurations of crystal structures using electron diffraction patterns by means of least-squares refinement.

A simple method is reported to determine the absolute configuration of the crystal structure from electron diffraction patterns taken from very small areas. The method is based on the differences in the Friedel reflections, which are in general much larger than for X-rays due to the dynamical behaviour of the electron scattering. We express the absolute configuration with a parameter similar to the one Flack (Acta Cryst. A 39 (1983) 876) introduced in X-ray crystallography. This parameter is added to a refinement procedure that uses a multi-slice calculation to calculate diffraction patterns. The validity and strength of the method are shown with simulated and experimental data sets of GaN in the [0 1 0]-zone and a more complex compound, Ce5Cu19P12 in the [0 0 1] zone.

Journal Article↗
PubMed2002

The N34S mutation of SPINK1 (PSTI) is associated with a familial pattern of idiopathic chronic pancreatitis but does not cause the disease.

BACKGROUND: Mutations in the PRSS1 gene explain most occurrences of hereditary pancreatitis (HP) but many HP families have no PRSS1 mutation. Recently, an association between the mutation N34S in the pancreatic secretory trypsin inhibitor (SPINK1 or PSTI) gene and idiopathic chronic pancreatitis (ICP) was reported. It is unclear whether the N34S mutation is a cause of pancreatitis per se, whether it modifies the disease, or whether it is a marker of the disease. PATIENTS AND METHODS: A total of 327 individuals from 217 families affected by pancreatitis were tested: 152 from families with HP, 108 from families with ICP, and 67 with alcohol related CP (ACP). Seven patients with ICP had a family history of pancreatitis but no evidence of autosomal dominant disease (f-ICP) compared with 87 patients with true ICP (t-ICP). Two hundred controls were also tested for the N34S mutation. The findings were related to clinical outcome. RESULTS: The N34S mutation was carried by five controls (2.5%; allele frequency 1.25%), 11/87 (13%) t-ICP patients (p=0.0013 v controls), and 6/7 (86%) affected (p<0.0001 v controls) and 1/9 (11%) unaffected f-ICP cases. N34S was found in 4/108 affected HP patients (p=0.724 v controls), in 3/27 (11%) with wild-type and in 1/81 (1%) with mutant PRSS1, and 4/67 ACP patients (all p>0.05 v controls). The presence of the N34S mutation was not associated with early disease onset or disease severity. CONCLUSIONS: The prevalence of the N34S mutation was increased in patients with ICP and was greatest in f-ICP cases. Segregation of the N34S mutation in families with pancreatitis is unexplained and points to a complex association between N34S and another putative pancreatitis related gene.

Adult↗