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Biomedical subjects

P De Jong

Publications and source records attributed to P De Jong.

15 recordsLinked to original sources
PubMed2007

Predictive modeling of Bacillus cereus spores in farm tank milk during grazing and housing periods.

The shelf life of pasteurized dairy products depends partly on the concentration of Bacillus cereus spores in raw milk. Based on a translation of contamination pathways into chains of unit-operations, 2 simulation models were developed to quantitatively identify factors that have the greatest effect on the spore concentration in milk. In addition, the models can be used to determine the reduction in concentration that could be achieved via measures at the farm level. One model predicts the concentration when soil is the source of spores, most relevant during grazing of cows. The other model predicts the concentration when feed is the main source of spores, most relevant during housing of cows. It was estimated that when teats are contaminated with soil, 33% of the farm tank milk (FTM) contains more than 3 log(10) spores/L of milk. When feed is the main source, this is only 2%. Based on the predicted spore concentrations in FTM, we calculated that the average spore concentration in raw milk stored at the dairy processor during the grazing period is 3.5 log(10) spores/L of milk and during the housing period is 2.1 log(10) spores/L. It was estimated that during the grazing period a 99% reduction could be achieved if all farms minimize the soil contamination of teats and teat cleaning is optimized. During housing, reduction of the concentration by 60% should be feasible by ensuring spore concentrations in feed below 3 log(10) spores/g and a pH of the ration offered to the cows below 5. Implementation of these measures at the farm level ensures that the concentration of B. cereus spores in raw milk never exceeds 3 log(10) spores/L.

Animals↗
PubMed2006

Improving farm management by modeling the contamination of farm tank milk with butyric acid bacteria.

Control of contamination of farm tank milk (FTM) with the spore-forming butyric acid bacteria (BAB) is important to prevent the late-blowing defect in semi-hard cheeses. The risk of late blowing can be decreased via control of the contamination level of FTM with BAB. A modeling approach was applied to identify an effective control strategy at the farm level. The simulation model developed was based on a translation of the contamination pathway into a chain of unit operations. Using various simulations, the effects of factors related to feed quality, feed management, cattlehouse hygiene, and milking practices on the contamination level of FTM were evaluated. Contamination level of silage was found to be the most important factor. When silage contains on average less than 3 log10 BAB/g, a basic pretreatment of udder teats before milking (approximately 75% removal of attached spores) is sufficient to assure an FTM contamination level below 1 BAB/mL. When silage contains more than 5 log10 BAB/g, it should not be fed, because it then becomes almost impossible to assure an FTM contamination level below 1 BAB/mL. Measures aimed at improving cattlehouse hygiene, the contamination via soil, and the contamination level of other feeds contribute only marginally to the control of the contamination of FTM with BAB. Application of the modeling methodology could be beneficial for the control of the contamination of FTM with other microorganisms such as Bacillus cereus.

Animals↗
PubMed2001

Co-constructing cooperation with mandated clients.

Dominant practice models for social work were originally developed and intended for work with voluntary clients. The professional literature indicates that use of these models with involuntary clients often alienates rather than engages. This article describes the use of solution-focused interviewing as a way to engage involuntary and mandated clients. A conversation with a court-ordered client is presented and analyzed to demonstrate how practitioners can begin the co-construction of cooperation with mandated clients through adopting a not-knowing posture, focusing on and amplifying what clients want and client strengths and successes, and asking relationship questions to generate possibilities for change specific to the mandated context. The ethical implications of this noncoercive, nonconfrontational approach are addressed, along with its implications for a view of how clients change.

Adult↗
PubMed2000

Masked fear words produce increased SCRs: an anomaly for Ohman's theory of pre-attentive processing in anxiety.

A. Ohman and J.J.F. Soares (1994) demonstrated that masked presentation of phobic pictures produces increased skin conductance responses (SCRs) in phobic subjects. A. Ohman (1993) explained this phenomenon in terms of a hypothetical "feature detector" that identifies physical characteristics of stimuli and activates the arousal system without involving significance evaluation or consciousness. By exposing spider phobics to spider words, general threat words, and neutral words instead of pictures, this explanation was tested. Words were presented both masked and unmasked while electrodermal activity was measured. Under unmasked conditions, SCRs were largest for spider words followed by general threat words, then neutral words. When masked, the difference between spider words and general threat words disappeared but SCRs remained significantly smaller for neutral words. It is concluded that activation of the arousal system by masked threat cues does not necessarily depend on their perceptual characteristics.

Adult↗
PubMed1999

Glutamine synthetase expression in perinatal spiny mouse liver.

The pronounced increase in the protein/mRNA ratio of ammonia-metabolising enzymes in rat liver in the last prenatal week represents a clear example of a post-transcriptional level of control of gene expression. Both the underlying mechanism, namely an increase in translational efficiency of the mRNA and/or enhanced stability of the protein, and its importance for perinatal adaptation are unknown. We investigated this process in spiny mouse liver, because the comparison of rat and spiny mouse can discriminate adaptively from developmentally regulated processes in the perinatal period. We focused on glutamine synthetase (GS) because of the conveniently small size of its mRNA. Prenatally, GS enzyme activity slowly accumulated to approximately 1.3 U x g-1 liver at birth and postnatally more rapidly to 5.5 U x g-1 at 2 weeks. Both phases of enzyme accumulation obeyed exponential functions. Western-blot analysis showed that changes in GS activity reflected changes in GS protein content. GS mRNA content of the liver was 45 fmol x g-1 at 2 weeks before birth and slowly declined to approximately 25 fmol x g-1 at 2 weeks after birth. The GS protein/mRNA ratio increased 2.5-fold prenatally and sixfold postnatally. Analysis of prenatal and postnatal polysome profiles revealed no evidence of GS mRNA-containing ribonucleoprotein particles. Instead, GS mRNAs were (fully) occupied by 12 ribosomes, indicating regulation at the level of elongation. The kinetics of GS protein accumulation, in conjunction with GS mRNA content, are consistent with an approximately sixfold increase in its rate of synthesis at birth as the result of a corresponding stimulation of the rate of elongation.

Animals↗
PubMed1995

Genomic structure of SAS, a member of the transmembrane 4 superfamily amplified in human sarcomas.

SAS is a recently identified member of the transmembrane 4 superfamily (TM4SF) that is frequently amplified in human sarcomas. To further its characterization and to confirm its classification, the genomic structure of the SAS gene was determined. The SAS gene covers approximately 3.2 kb of DNA. It contains six exons within its translated region, three of which are highly conserved in the TM4SF. 5' to the translation start site are two putative transcription start sites, two CCAAT consensus sequences, and potential binding sites for both Sp1 and ATF transcription factors. Comparison of SAS organization to human ME491, CD9, and CD53 and murine CD53 and TAPA-1 confirms that SAS is a member of this family of genes and is consistent with the theory that these genes arose through duplication and divergent evolution.

Amino Acid Sequence↗
PubMed1992

The clinical significance of Haemophilus influenzae and H. parainfluenzae isolated from the sputum of adult patients at an urban general hospital.

Fifty-seven patients, from whose sputum Haemophilus influenzae (49 cases) or Haemophilus parainfluenzae (8 cases) was isolated during a 7-month period, were studied. In the majority of cases there were well-defined predisposing factors to respiratory tract colonisation or infection with the isolates, in particular bronchiectasis and chronic obstructive airways disease. Colonisation of the airways, bronchopneumonia in patients with underlying lung disease, acute lobar pneumonia, and postoperative chest infections were the commonest clinical diagnoses. Primary acute lobar pneumonia with these organisms alone was uncommon. All of the H. influenzae isolates were nontypeable, and there was a wide range of biotypes of both organisms. Three H. influenzae isolates produced beta-lactamase, and there was, in general, a low incidence of resistance to a wide range of antimicrobial agents on disc susceptibility testing.

Adult↗
PubMed1992

Cloning and characterization of the Ewing's sarcoma and peripheral neuroepithelioma t(11;22) translocation breakpoints.

Ewing's sarcoma (ES) and peripheral neuroepithelioma (PN) are related tumors, possibly of neural crest origin, which are cytogenetically characterized by the specific translocation t(11;22)(q24;q12). The cos5 locus, previously identified in the vicinity of the chromosome 22 breakpoint of this translocation, was shown by in situ hybridization on interphase nuclei to lie between VIIIF2 and LIF, two loci located on either side of the breakpoint and at a distance of less than 2,000 kb. The progressive expansion of this locus by chromosome walking led to the construction of a 300 kb contig, which finally crossed the breakpoint. The subsequent cloning of the two translocation junction fragments of a PN, followed by the molecular characterization of the translocation breakpoints of 20 ES and PN, showed that most chromosome 22 breakpoints are clustered within a small, 2 kb region. In contrast, the chromosome 11 breakpoints are scattered over a region of at least 40 kb. The translocation leads to the synthesis of chimeric transcript that links sequences from chromosomes 22 and 11. Finally, no evidence was found of any specific difference in the position of ES and PN translocation breakpoints.

Bone Neoplasms↗
PubMed1992

Rapid isolation of cosmids from defined subregions by differential Alu-PCR hybridization on chromosome 22-specific library.

A method based on the differential screening of a chromosome-specific cosmid library with amplified inter-Alu sequences obtained from a set of somatic cell hybrids has been developed to target the isolation of probes from predefined subchromosomal regions. As a model system, we have used a chromosome 22-specific cosmid library and four cell hybrids containing different parts of this chromosome. The procedure has identified cosmids that demonstrate differential hybridization signals with Alu-PCR products from these cell hybrids. We show, by in situ hybridization or individual mapping, that their hybridization pattern is indicative of their sublocalization on chromosome 22, thus resulting in a large enrichment factor for the isolation of probes from specific small chromosome subregions. Depending on the local Alu-sequence density, from 3 to 10 independent loci per megabase of genome can thus be identified.

Animals↗
PubMed1990

Waning of panic sensations during prolonged hyperventilation.

Recent theories about panic emphasize that a hyperventilatory positive feedback loop is involved in panic: catastrophic misinterpretation of bodily sensations may trigger anxiety, anxiety may stimulate hyperventilation, hyperventilation may promote the salience of feared sensations etc. Such models leave unexplained how and when panics come to an end. It was hypothesised that panic with hyperventilation may end because pronounced hyperventilation becomes, in the course of time, less powerful in generating perceivable bodily sensations. Twenty healthy subjects hyperventilated forcefully and experienced clear panic symptoms as defined by DSM IIIR. When pCO2 was kept 55% below base line for 90 min, panic symptoms waned. The mean intensity of the symptoms declined as did the number of symptoms occurring. No panic symptoms were observed in the control group (n = 20) who ventilated normally. In so far as hyperventilation is involved in the positive feedback loops that characterize panic, panic attacks may be time-limited because sensations induced by hyperventilation become less salient even if massive hyperventilation continues. As to the explanation of the reported phenomenon, it is suggested that, apart from habituation, local physiological changes due to prolonged hyperventilation may produce a decrease in interoceptive input.

Adult↗
PubMed1990

Hemisphere preference, phobia, and depression.

The present study was undertaken in order to examine whether depression and anxiety are related to preference for a right hemisphere mode of thinking. On the basis of a paper-and-pencil test presumably measuring hemisphere preference (Preference Test; Zenhausern, 1978), normal subjects (N = 75) were assigned to a group characterized by a left hemisphere thinking style, a group characterized by a right hemisphere thinking style and a group with mixed tendencies (left and right hemisphere tendencies). Additionally, subjects completed the Fear Questionnaire and the Depression Symptom Inventory. It was found that subjects with a right hemisphere thinking style reported more depressive and fear symptoms than subjects with a left hemisphere thinking style. This finding is in line with theories which assume that the right hemisphere is characterized by a negative, dysphoric emotional tendency.

Adult↗
PubMed1985

The different intracellular action potentials of fast and slow muscle fibres.

The time course of the intracellular action potential was studied quantitatively, because it is an important factor in the generation of electromyographic signals. In in vivo preparations of the m. EDL and m. soleus of the rat single motor units were stimulated and intracellular action potentials were recorded in muscle fibres belonging to those motor units. In this arrangement it was possible to relate the intracellular action potential to the fibre type. The intracellular action potentials of fast twitch glycolytic (FTG) EDL and of slow soleus fibres were described, using 8 characteristics. All characteristics but one differed significantly between the two fibre populations. Comparing characteristics of intracellular action potentials of FTG fibres with slow fibres, it is concluded that: the resting membrane potential is more negative; the amplitude of the action potential is larger; the maximum rates of depolarization and repolarization are higher; and the shape of the repolarization phase is more variable.

Action Potentials↗
PubMedDate not supplied

Hepatitis B vaccination in Down's syndrome and other mentally retarded patients.

The immune response after vaccination with H-B-VAX (20 micrograms, Months 0, 1 and 6) was investigated in 23 Down's syndrome patients and compared to that in 30 other mentally retarded patients and 32 staff members. About 90% of Down's syndrome and other mentally retarded patients and 100% of staff members had anti-HBs at Month 9, but anti-HBs less than 10 IU per liter were found in 6/23 (26.1%) of Down's syndrome, 7/30 (23.3%) of other mentally retarded patients, in contrast to 2/32 (6.2%) of staff members. No differences in anti-HBs response with regard to sex and age were observed in staff members, but geometric mean titers of anti-HBs were lower in older Down's syndrome and other mentally retarded patients, and in male Down's syndrome patients. Supplementary vaccination is necessary in these individuals to obtain "protective levels" of anti-HBs.

Adolescent↗