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Biomedical subjects

P de Jong

Publications and source records attributed to P de Jong.

At least 19 recordsLinked to original sources
PubMed2006

Minimal ProtoHox cluster inferred from bilaterian and cnidarian Hox complements.

Bilaterian animals have a Hox gene cluster essential for patterning the main body axis, and a ParaHox gene cluster. Comparison of Hox and ParaHox genes has led workers to postulate that both clusters originated from the duplication of an ancient cluster named ProtoHox, which contained up to four genes with at least the precursors of anterior and posterior Hox/ParaHox genes. However, the way in which genes diversified within the ProtoHox, Hox and ParaHox clusters remains unclear because no systematic study of non-bilaterian animals exists. Here we characterize the full Hox/ParaHox gene complements and genomic organization in two cnidarian species (Nematostella vectensis and Hydra magnipapillata), and suggest a ProtoHox cluster simpler than originally thought on the basis of three arguments. First, both species possess bilaterian-like anterior Hox genes, but their non-anterior genes do not appear as counterparts of either bilaterian central or posterior genes; second, two clustered ParaHox genes, Gsx and a gene related to Xlox and Cdx, are found in Nematostella vectensis; and third, we do not find clear phylogenetic support for a common origin of bilaterian Cdx and posterior genes, which might therefore have appeared after the ProtoHox cluster duplication. Consequently, the ProtoHox cluster might have consisted of only two anterior genes. Non-anterior genes could have appeared independently in the Hox and ParaHox clusters, possibly after the separation of bilaterians and cnidarians.

Animals↗
PubMed2006

National survey on the natural radioactivity and 222Rn exhalation rate of building materials in The Netherlands.

The present study reports on results of a nation-wide survey on the natural radioactivity concentrations and Rn exhalation rates of the prevailing building materials in the Netherlands. In total 100 samples were taken and analyzed for the activity concentrations of Ra, Ra, Th, and K and for their Rn exhalation rate. The sampled materials consisted of gypsum products, aerated concrete, sand-lime and clay bricks, mortars and concrete, representing about 95% of the stony building materials used in the construction of Dutch homes. The laboratory analyses were performed according to two well-documented standard procedures, the interlaboratory reproducibility of which is found to be within 5% on average. The highest radionuclide concentrations were found in a porous inner wall brick to which fly ash was added. The second highest were clay bricks with average Ra and Ra levels around 40 Bq kg. Concrete and mortar show the highest exhalation rates with a fairly broad range of 1 to 13 microBq (kg s). Low natural radioactivity levels are associated with either natural gypsum (products) or gypsum from flue gas desulphurization units, and low exhalation rates with clay bricks. To evaluate the radiological impact the radioactivity concentrations in each sample were combined into a so-called dose factor, representing the absorbed dose rate in a room with a floor, walls and ceiling of 20 cm of the material in question. For that purpose, calculations with the computer codes MCNP, Marmer and MicroShield on the specific absorbed dose rates were incorporated in the paper. The results of these codes corresponded within 6% and average values were calculated at 0.90, 1.10, and 0.080 nGy h per Bq kg for the U series, the Th series, and K, respectively. Model calculations on the external dose rate, based on the incidence of the various building materials in 1,336 living rooms, are in accordance with measured data.

Air Pollutants, Radioactive↗
PubMed2006

Construction of a medium-density horse gene map.

A medium-density map of the horse genome (Equus caballus) was constructed using genes evenly distributed over the human genome. Three hundred and twenty-three exonic primer pairs were used to screen the INRA and the CHORI-241 equine BAC libraries by polymerase chain reaction and by filter hybridization respectively. Two hundred and thirty-seven BACs containing equine gene orthologues, confirmed by sequencing, were isolated. The BACs were localized to horse chromosomes by fluorescent in situ hybridization (FISH). Overall, 165 genes were assigned to the equine genomic map by radiation hybrid (RH) (using an equine RH(5000) panel) and/or by FISH mapping. A comparison of localizations of 713 genes mapped on the horse genome and on the human genome revealed 59 homologous segments and 131 conserved segments. Two of these homologies (ECA27/HSA8 and ECA12p/HSA11p) had not been previously identified. An enhanced resolution of conserved and rearranged chromosomal segments presented in this study provides clarification of chromosome evolution history.

Animals↗
PubMed2005

Interlaboratory comparison of three methods for the determination of the radon exhalation rate of building materials.

In this study three methods for the determination of the radon (222Rn) exhalation rate of building materials are compared. All three are so-called purge-and-trap methods in which the sample is enclosed in a container from which the exhaled radon is continuously purged by a constant flow of nitrogen gas. The outflowing radon is directed through a trapping agent, and the radon exhalation rate is subsequently calculated from the trapped activity. The main differences between the three methods are the trapping agent (silica gel, charcoal), trapping temperature (liquid nitrogen, room temperature), trapping period (30 min to 10 d), analytical method to determine the trapped activity (liquid scintillation counting, gamma ray spectrometry, total gamma counting) and the sample counting times (1 to 16 h). The repeatability and intralaboratory reproducibility are determined for one of the methods and amount to 3.1% and 4.3%, respectively. The intralaboratory reproducibility, derived from five samples with a radon release rate up to 450 microBq s(-1), was found to be 5.6% on average (range 3 to 8%). These figures are close to the combined standard uncertainty of the individual results that vary between 3 to 6%, depending on the method and method variables such as trapping period and the uncertainty of the calibration source. Furthermore, another 10 commercially available building materials were analyzed to investigate the correlation between the applied methods. Using linear regression analysis, it was found that the slope deviated not more than 10% from the one to one correspondence line. The results show that measurements of the exhalation rate can be carried out with a large degree of accuracy provided sufficient care is taken for a well-documented standard method.

Calibration↗
PubMed2002

Prediction of the adherence, growth and release of microorganisms in production chains.

The aim of this study was to develop a mathematical model that describes the bacterial contamination of food as a result of adherence, growth and release of bacteria in process equipment. The model developed can be applied to control the bacterial quality of food products produced in process chains in which the final contamination of the product is governed by growth and heat-induced destruction of bacteria. To set up the model, experiments were carried out with a plate heat exchanger using milk inoculated with Streptococcus thermophilus. The growth rate of S. thermophilus in milk could be described accurately by the modified expanded model of Ratkowsky. The observed increase in the concentration of S. thermophilus in milk at the outlet of the plate heat exchanger could be described quantitatively by the model. To predict the contamination of the product, the model was integrated into NIZO-PCS (Process Chain Simulator). The results of computer simulations were validated by a number of measurements in a cheese factory. It turned out that the agreement between the measured and calculated concentrations of S. thermophilus was sufficient for the model to be used for predictions in industrial production chains.

Animals↗
PubMed2002

[Economical analyses in interventional radiology].

Considerations about the relation between benefit and expenses are also gaining increasing importance in interventional radiology. This review aims at providing a survey about the published data concerning economical analyses of some of the more frequently employed interventions in radiology excluding neuroradiological and coronary interventions. Because of the relative scarcity of literature in this field, all identified articles (n = 46) were included without selection for methodological quality. For a number of radiological interventions the cost-effectiveness has already been demonstrated, e. g., PTA of femoropopliteal and iliac artery stenoses, stenting of renal artery stenoses, placement of vena-cava filters, as well as metal stents in malignant biliary and esophageal obstructions. Conflicting data exist for the treatment of abdominal aortic aneurysms. So far, no analysis could be found that directly compares bypass surgery versus PTA + stent in iliac arteries.

Angioplasty, Balloon↗
PubMed2001

Large-insert BAC/YAC libraries for selective re-isolation of genomic regions by homologous recombination in yeast.

We constructed representative large-insert bacterial artificial chromosome (BAC) libraries of two human pathogens (Trypanosoma brucei and Giardia lamblia) using a new hybrid vector, pTARBAC1, containing a yeast artificial chromosome (YAC) cassette (a yeast selectable marker and a centromere). The cassette allows transferring of BACs into yeast for their further modification. Furthermore, the new hybrid vector provides the opportunity to re-isolate each DNA insert without construction of a new library of random clones. Digestion of a BAC DNA by an endonuclease that has no recognition site in the vector, but which deletes most of the internal insert sequence and leaves the unique flanking sequences, converts a BAC into a TAR vector, thus allowing direct gene isolation. Cotransformation of a TAR vector and genomic DNA into yeast spheroplasts, and subsequent recombination between the TAR vector's flanking ends and a specific genomic fragment, allows rescue of the fragment as a circular YAC/BAC molecule. Here we prove a new cloning strategy by re-isolation of randomly chosen genomic fragments of different size from T. brucei cloned in BACs. We conclude that genomic regions of unicellular eukaryotes can be easily re-isolated using this technique, which provides an opportunity to study evolution of these genomes and the role of genome instability in pathogenicity.

Animals↗
PubMed2001

SPTLC1 is mutated in hereditary sensory neuropathy, type 1.

Hereditary sensory neuropathy type 1 (HSN1, MIM 162400; ref. 1) genetically maps to human chromosome 9q22 (refs. 2-4). We report here that the gene encoding a subunit of serine palmitoyltransferase is located within the HSN1 locus, expressed in dorsal root ganglia (DRG) and mutated in HSN1.

Acyltransferases↗
PubMed2001

Heat inactivation data for Mycobacterium avium subsp. paratuberculosis: implications for interpretation.

AIMS: We discuss several factors that are critical for heat inactivation experiments and which should be taken into account for future research. METHODS AND RESULTS: On the basis of examples from the literature we discuss critical factors influencing the calculated heat inactivation of Mycobacterium avium subsp. paratuberculosis (MAP). Furthermore, using a modelling approach, we show that tailing of the inactivation curve of MAP is caused by the presence of cell clumps and not by a more heat-resistant cell fraction. CONCLUSIONS: The experimental conditions of the MAP heat inactivation studies of different research groups vary significantly and lead to considerable differences in results and conclusions. Therefore, a more consensual approach should be employed in future studies. In addition, our model on clumping of MAP can be used to predict the decimal reduction of MAP during heat treatment and to study the effect of clumping on other lethal effects. SIGNIFICANCE AND IMPACT OF THE STUDY: We discuss several factors that should be carefully considered in heat resistance experiments. This is essential for a thorough interpretation of results from experiments and should be given proper attention in future experiments and publications on this topic.

Animals↗
PubMed2000

Influence of high-intensity ultrasound and heat treatment in continuous flow on fat, proteins, and native enzymes of milk.

The effect of continuous flow high-intensity ultrasound (with and without heat generation) on alkaline phosphatase, gamma-glutamyltranspeptidase, lactoperoxidase, whey proteins (alpha-lactalbumin and beta-lactoglobulin), casein, and fat was studied in milk. Results were compared with those obtained using a conventional heating system having similar processing conditions. Hardly any effect on enzymes was observed when ultrasound was applied without heat generation. The highest denaturation of enzyme and whey proteins was found in samples subjected to ultrasound and heat. At 61, 70, and 75.5 degrees C a synergistic effect between ultrasound and heat was observed for the inactivation of alkaline phosphatase, gamma-glutamyltranspeptidase, and lactoperoxidase, respectively. A noticeable synergism between ultrasound and heat was detected for alpha-lactalbumin and beta-lactoglobulin denaturation. No changes in the casein were observed after any of the conditions assayed. As a consequence of ultrasound effects, a substantial reduction (up to 81.5%) in the size of the fat globule was observed. When 70 and 75.5 degrees C were achieved during high-intensity ultrasonic homogenization, a better particle distribution was observed as compared to that obtained at lower temperatures. This work describes the influence of continuous flow high-intensity ultrasound on important milk components as a first step for future processing applications.

Animals↗
PubMed1999

Recent amplification of the human FRG1 gene during primate evolution.

There is evidence of multiple copies of the FSHD Region Candidate Gene 1 (FRG1) in humans. Analysis of human FRG1 ESTs showed many of them to be non-processed pseudogenes dispersed throughout the genome. To determine when the amplification of FRG1 occurred, we used a PCR-based approach to identify FRG1 sequences from great apes, chimpanzee, gorilla and orang-utan, and an Old World monkey, Macaca mulatta. In common with humans, multiple copies of FRG1 were detected in the great apes. However, in Macaca mulatta, only two FRG1 loci were identified, one presumed to be the homologue of the human chromosome 4q gene. This is strikingly similar to the distribution of a dispersed 3.3-kb repeat family in primates. A member of this family, D4Z4, maps to the subtelomeric region of 4q, in close proximity to FRG1. We propose that an ancestral duplication of distal 4q included FRG1. This duplication is present in Macaca mulatta whose divergence from hominoids is thought to have occurred at least 33 million years ago. We propose that this telomeric region then underwent further amplification and dispersion events in the great ape lineage, with copies of FRG1 and the 3.3-kb repeats being localized in heterochromatic regions.

Animals↗
PubMed1999

Genetic mapping of the copper toxicosis locus in Bedlington terriers to dog chromosome 10, in a region syntenic to human chromosome region 2p13-p16.

Abnormal hepatic copper accumulation is recognized as an inherited disorder in man, mouse, rat and dog. The major cause of hepatic copper accumulation in man is a dysfunctional ATP7B gene, causing Wilson disease (WD). Mutations in the ATP7B genes have also been demonstrated in mouse and rat. The ATP7B gene has been excluded in the much rarer human copper overload disease non-Indian childhood cirrhosis, indicating genetic heterogeneity. By investigating the common autosomal recessive copper toxicosis (CT) in Bedlington terriers, we have identified a new locus involved in progressive liver disease. We examined whether the WD gene ATP7B was also causative for CT by investigating the chromosomal co-localization of ATP7B and C04107, using fluorescence in situ hybridization (FISH). C04107 is an anonymous microsatellite marker closely linked to CT. However, BAC clones containing ATP7B and C04107 mapped to the canine chromosome regions CFA22q11 and CFA10q26, respectively, demonstrating that WD cannot be homologous to CT. The copper transport genes CTR1 and CTR2 were also excluded as candidate genes for CT since they both mapped to canine chromosome region CFA11q22. 2-22.5. A transcribed sequence identified from the C04107-containing BAC was found to be homologous to a gene expressed from human chromosome 2p13-p16, a region devoid of any positional candidate genes.

Adenosine Triphosphatases↗
PubMed1998

Comparison of the footpump suction evacuator with the manual vacuum aspirator for uterine evacuation.

OBJECTIVE: To compare the efficacy of a novel footpump suction evacuator with the manual vacuum aspirator in the management of women with incomplete abortions requiring uterine evacuation. DESIGN: A prospective comparative analysis of women allocated to either manual vacuum aspiration of the uterus or footpump suction evacuation, following first- or second-trimester incomplete abortion. SETTING: The gynaecology casualty theatre, Groote Schuur Hospital, Cape Town. PATIENTS: 121 women with first- or second-trimester abortions. Patients with signs of septic abortion were excluded from the study. INTERVENTIONS: Uterine evacuation under general anaesthesia by means of a manual vacuum aspirator or a novel footpump suction evacuator. OUTCOME MEASURES: Endpoints assessed included duration of the procedures, ease of evacuation, estimated blood loss, volume of products of conception obtained, postoperative complications of the procedures and amount of analgesia required postoperatively. RESULTS: The manual vacuum aspirator and footpump suction evacuator appeared equally effective for uterine evacuation. There were no significant differences in the endpoints assessed. CONCLUSIONS: Both methods appear equally effective for uterine evacuation.

Abortion, Incomplete↗
PubMed1997

A high-resolution PAC and BAC map of the SCA2 region.

The spinocerebellar ataxia type 2 (SCA2) gene has been localized to chromosome 12q24.1. To characterize this region and to aid in the identification of the SCA2 gene, we have constructed a 3.9-Mb physical map, which covers markers D12S1328 and D12S1329 known to flank the gene. The map comprises a contig of 84 overlapping yeast artificial chromosomes (YACs), P1 artificial chromosomes (PACs), and bacterial artificial chromosomes (BACs) onto which we placed 82 PCR markers. We localized eight genes and expressed sequence tags on this map, many of which had not been precisely mapped before. In contrast to YACs, which showed a high degree of chimerism and deletions in this region, PACs and BACs were stable. Only 1 in 65 PACs contained a small deletion, and 2 in 18 BACs were chimeric. The high-resolution physical map, which was used in the identification of the SCA2 gene, will be useful for the positional cloning of other disease genes mapped to this region.

Ataxins↗
PubMed1997

Bovine-heart NADH:ubiquinone oxidoreductase is a monomer with 8 Fe-S clusters and 2 FMN groups.

The availability of the amino-acid sequences of a number of mitochondrial and bacterial NADH:ubiquinone oxidoreductases (Complex I), the sequence similarities of five of the essential subunits of Complex I with subunits of [NiFe]hydrogenases and [Fe]hydrogenases, as well as some long-standing controversies about the precise EPR properties and stoichiometries of the iron-sulfur clusters in Complex I have led us to propose a new structural and functional model for this complicated enzyme. The functional unit is a monomer comprising 8 different Fe-S clusters and 2 FMN molecules as prosthetic groups. The electron-input pathway, as well as part of the electron-transfer components, seem largely inherited from bacterial NAD(+)-reducing hydrogenases. The essential electron-transfer components of the electron-output pathway are located in the TYKY subunit. This subunit is proposed to hold both iron-sulfur clusters 2 and to render the enzyme the ability to perform coupled electron transfer. Based on earlier observed similarities (Albracht. S.P.J. (1993) Biochim. Biophys. Acta 1144, 221-224) of the 49 kDa subunit and the PSST subunit with, respectively, the large and small subunits of [NiFe]hydrogenases, it is proposed that the 49 kDa/PSST subunit couple provides Complex I with an ancient proton-transfer pathway.

Amino Acid Sequence↗
PubMed1997

EEG correlates of a paper-and-pencil test measuring hemisphericity.

The present study examined the validity of the Preference Test (PT), a questionnaire that intends to measure the extent to which subjects rely on right-hemisphere and left-hemisphere cognitions. Normal subjects (N = 20) completed the PT and were then assigned to a group with a relatively strong preference for left-hemisphere cognitions or a group with a relatively strong preference for right-hemisphere cognitions. Next, background EEG was recorded. Subjects with a preference for right-hemisphere cognitions were found to display relatively more alpha power over the left than over the right frontal areas, compared to subjects with a preference for left-hemisphere cognitions. This finding provides partial support for the validity of the PT.

Adolescent↗