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Biomedical subjects

P Zwart

Publications and source records attributed to P Zwart.

At least 19 recordsLinked to original sources
PubMed2006

Inclusion body disease in snakes: a review and description of three cases in boa constrictors in Belgium.

Inclusion body disease, a fatal disorder in Boidae, is reviewed, and three cases in boa constrictors, the first reported cases in Belgium, are described. The snakes showed nervous signs, and numerous eosinophilic intracytoplasmic inclusions, which are considered to be characteristic of the disease, were found in the liver and pancreas. The disease is suspected to be caused by a retrovirus, but transmission electron microscopic examinations of several tissues from one of the snakes did not reveal particles with a typical retroviral morphology.

Animals↗
PubMed2006

[Developmental delay in breastfed children due to inadequate diet of the mother].

Two infant boys of 7 and 12 months respectively who presented with symptoms of failure to thrive and developmental delay were diagnosed with vitamin B12 deficiency. This deficiency is a rare condition in infants living in developed countries. It does occur, however, in infants who are breastfed by mothers with an inadequate diet. Both of the children studied were breastfed by vegetarian mothers. Following vitamin suppletion, both children showed signs of recovery. The importance of considering vitamin deficiencies in similar infants presenting with failure to thrive is emphasized. Moreover, maternal dietary habits in breastfed children should be checked. To prevent irreversible neurological damage, early recognition of any nutritional deficiencies is important.

Adult↗
PubMed2005

[Causes, treatment and clinical outcome in infants admitted because of excessive crying to the paediatric department of the Isala clinics, Zwolle, the Netherlands, 1997/'03].

OBJECTIVE: Evaluation of the strategy of admitting excessively crying infants after no improvement is seen following measures taken by the family physician. DESIGN: Retrospective. METHOD: By studying medical records, data were collected for all infants who were admitted to the paediatric department of the Isala clinics in Zwolle because of excessive crying in the period 1997/'03. Excessive crying here was defined as 'crying that was regarded by the parents as excessive', whereby strict time criteria did not have to be met. RESULTS: In the study period of 6.5 years, 88 children were admitted because of excessive crying: 51 boys and 37 girls, with an average age of 10 weeks (range: 0.5-40). Measures taken without success prior to referral included: hypoallergenic feeding in 51 cases (58%), alternative medical treatment in 18 (20%) and antacids in 9 (10%). In 3 patients (3%) a possible cause of the excessive crying was identified and improvement occurred after treatment: cow's milk allergy (n = 2) and recurrent respiratory tract infections caused by a humoral immunodeficiency (n = 1). Clinical indications for an underlying cause were present in another 8 patients but this could be neither confirmed nor excluded. In 77 patients (88%) the crying rapidly improved within a few days without a specific intervention. In most children, hypoallergenic feeding could be replaced by regular cow's milk formulas without any problems. After discharge, there were so re-admissions for excessive crying (11%). CONCLUSION: In the majority of infants admitted to hospital for excessive crying, no underlying cause was found and the crying rapidly improved within a few days without a specific intervention. We therefore recommend that excessively crying infants merely be observed clinically for several days. There is no indication for immediate diagnostic or therapeutic interventions. It is important, however, to counsel parents about their own anxiety and distress and the influence these may have on the infant's crying behaviour.

Crying↗
PubMed2004

[Excessive crying in infants: a problem for both parents and children (only rarely caused by milk allergy)].

According to a systematic review published in 1998, hypoallergenic formula can be useful in treating infants who cry excessively. For this reason it is normal practice in the Netherlands to prescribe hypoallergenic formula for these infants. However, two of the three studies on which this systematic review was based were carried out in specialist paediatric allergy centres where there is a higher chance of encountering food allergy than in normal well-baby clinics. The third study was carried out in a well-baby clinic but only included babies who cried for more than 3 hours a day on more than 3 days per week. Experience with crying diaries has shown that by no means all babies who cry excessively according to their parents satisfy these criteria. It is not known if prescribing hypoallergenic formula is a useful intervention in infants whose parents report that they cry excessively. The tension and distress felt by the parents of infants who cry excessively are also important factors. In our opinion, support and guidance for the parents is a more effective treatment for excessive crying in infants than intervention with hypoallergenic formula.

Adult↗
PubMed2001

Assessment of the husbandry problems of reptiles on the basis of pathophysiological findings: a review.

Many health problems in animals are related to management and feeding. A large number of husbandry problems in reptiles lead to pathophysiological situations. Assessment of the husbandry problems of reptiles involves detective work that can only be achieved as a result of close cooperation and exchange of information between the owner and the pathologist. Reptiles, being ectothermic, depend for their physiological functioning largely on the quality of their surroundings. There are a large number of factors which influence the normal functioning of a reptile both in nature and in captivity. These factors can be described in terms of primary and secondary factors. Primary factors are the construction of terraria, light, heat, food, and water, and grouping of animals. Secondary factors are daylight regimen, arrangement of heating elements, type and composition of food, quality of water, and freedom from stress. Also important are ventilation, humidity, sites for resting and/or hiding, structure of the floor and of rocks, and branches for climbing activities. Hygiene is also an important aspect because poor hygiene often is directly related to problems. All these factors are dealt with in this review.

Animal Diseases↗
PubMed2000

[Underlying cow's milk protein intolerance in excessively crying infants; desirable and undesirable effects of an elimination diet].

In three infants with excessive crying, two girls aged 3 and 13 months and a boy aged 5 weeks, feeding with a hypoallergenic formula was started because cow's milk protein intolerance was suspected. Yet in two of the cases, another explanation for the excessive crying, notably parental distress, was more likely based on the history. In these 2 cases, no provocation test with cow's milk had been performed, and the hypoallergenic formula had been continued for a prolonged period of time (without introduction of solid foods), even though the excessive crying had not ceased. Prolonged feeding with the hypoallergenic formula when cow's milk protein intolerance is not confirmed by appropriate provocation testing, may strengthen the parents' misconception that their baby has severe food intolerance, causing unnecessary delay in the introduction of solid foods. This may hamper the normal development of taste and oral motor development.

Crying↗
PubMed2000

Structural basis for substrate specificity differences of horse liver alcohol dehydrogenase isozymes.

A structure determination in combination with a kinetic study of the steroid converting isozyme of horse liver alcohol dehydrogenase, SS-ADH, is presented. Kinetic parameters for the substrates, 5beta-androstane-3beta,17beta-ol, 5beta-androstane-17beta-ol-3-one, ethanol, and various secondary alcohols and the corresponding ketones are compared for the SS- and EE-isozymes which differ by nine amino acid substitutions and one deletion. Differences in substrate specificity and stereoselectivity are explained on the basis of individual kinetic rate constants for the underlying ordered bi-bi mechanism. SS-ADH was crystallized in complex with 3alpha,7alpha,12alpha-trihydroxy-5beta-cholan -24-acid (cholic acid) and NAD(+), but microspectrophotometric analysis of single crystals proved it to be a mixed complex containing 60-70% NAD(+) and 30-40% NADH. The crystals belong to the space group P2(1) with cell dimensions a = 55.0 A, b = 73.2 A, c = 92.5 A, and beta = 102.5 degrees. A 98% complete data set to 1.54-A resolution was collected at 100 K using synchrotron radiation. The structure was solved by the molecular replacement method utilizing EE-ADH as the search model. The major structural difference between the isozymes is a widening of the substrate channel. The largest shifts in C(alpha) carbon positions (about 5 A) are observed in the loop region, in which a deletion of Asp115 is found in the SS isozyme. SS-ADH easily accommodates cholic acid, whereas steroid substrates of similar bulkiness would not fit into the EE-ADH substrate site. In the ternary complex with NAD(+)/NADH, we find that the carboxyl group of cholic acid ligates to the active site zinc ion, which probably contributes to the strong binding in the ternary NAD(+) complex.

Alcohol Dehydrogenase↗
PubMed2000

Structure of CnCn+2Cn-type (n = even) beta'-triacylglycerols.

The crystal structures of the beta' phase of CLC (1, 3-didecanoyl-2-dodecanoylglycerol) and MPM (1, 3-ditetradecanoyl-2-hexadecanoylglycerol) have been determined from single-crystal X-ray diffraction and high-resolution X-ray powder diffraction data, respectively. Both these crystals are orthorhombic with space group Iba2 and Z = 8. The unit-cell parameters of beta'-CLC are a = 57.368 (6), b = 22.783 (2) and c = 5.6945 (6) A and the final R value is 0.175. The unit-cell parameters of beta'-MPM are a = 76.21 (4), b = 22.63 (1) and c = 5.673 (2) A and the final R(p) value is 0.057. Both the beta'-CLC and beta'-MPM molecules are crystallized in a chair conformation, having a bend at the glycerol moiety. The zigzag planes of the acyl chains are orthogonally packed, as is typical for a beta' phase. Furthermore, unit-cell parameters of some other members of the C(n)C(n+2)C(n)-type triacylglycerol series have been refined on their high-resolution X-ray powder diffraction pattern. Finally, the crystal structures are compared with the currently known structures and models of triacylglycerols.

Crystallography, X-Ray↗
PubMed2000

Improving the user interface to increase patient throughput.

One of the main goals of a radiology department is to optimize patient throughput. We have observed a number of factors that reduce patient throughput, one of them being suboptimal system usage. In this article, we distinguish and discuss two ways to reduce suboptimal operation: improved design of the user-interface and active support for learning during system usage, i.e., during examinations. We outline the rationale for this by looking at the current situation and trends in radiology departments. We have based our work firmly on the principles of user-centered design. Observations, task modeling, user involvement, and prototyping have been undertaken.

Efficiency, Organizational↗
PubMed2000

[Chytridiomycosis in amphibians--first report in Europe].

Declining of amphibian populations is a worldwide phenomenon. A cutaneous mycosis as a cause of death in free-living amphibians as well as in captive ones due to an chytrid fungus (Batrachochytrium dendrobatidis) was reported at first in 1998. This infections were reported hitherto from Australia, North, Central and South America. This is the first report on chytrid infections in captive anurans from Europe. Dendrobates auratus and D. pumilo imported from Costa Rica and P. vittatus imported from French Guayana died with chytridiomycosis within a week after arrival in Europe. Batrachocytrium was also found on captive bred frogs in Germany and Belgium. Clinical signs, diagnosis and conclusions for protecting free-living amphibian populations and captive frogs are discussed.

Animals↗
PubMed1997

Effect of lossy data compression on quantitative coronary measurements.

With the accepted use of (lossy) data compression at low compression factors (2, 3 and 4 on the Philips DCI), the question was posed whether higher lossy compression ratios can also be used without statistically affecting the results of quantitative coronary arteriography. In this study the influence of two data compression schemes (LOT and JPEG) at three different compression factors (5, 8 and 12) on coronary measurements was assessed with the Automated Coronary Analysis (ACA) package. A series of 30 original acquired digital images were compressed and decompressed at the different factors, and together with the original non-compressed images processed using the ACA package. In these images a total of 37 obstructed coronary segments were analyzed twice to assess the intra-observer variabilities in the obstruction and reference diameters and in the percent diameter stenosis. The results of the first and second measurements in each image were averaged, and from the differences in corresponding images with different compression ratios, the inter-compression variability was obtained. The results show that the intra-observer systematic errors in the absolute diameters are all small (< 0.07 mm), and statistically not significantly different. The intra-observer random errors for the compressed/decompressed series, however, were all larger (up to 0.21 mm) than for the original series (< 0.13 mm). Statistically significant differences in the intra-observer random errors were found for the JPEG compression scheme at a compression ratio of 5 and for the LOT scheme at a compression ratio of 12. The inter-compression systematic errors in the absolute diameter measurements were also small (< 0.07 mm) and not significant, while the random errors were found to be high in the range between 0.23 mm and 0.31 mm. Given the higher intra-observer variabilities for the compressed/decompressed image series as compared to original images, and the fact that all inter-compression variabilities were found to be so high, we must conclude that the higher compression ratios affect the results of QCA in a negative sense. In conclusion, the use of lossy data compression with JPEG or LOT compression schemes at ratios 5, 8 and 12 must be discouraged for QCA.

Algorithms↗
PubMed1996

Immunohistochemical method for detecting lesions in the prostate gland of bulls treated with diethylstilbestrol-dipropionate.

Hyperplastic and metaplastic lesions in the prostate gland of bulls are used as morphological evidence for the illegal administration of oestrogens or compounds with oestrogenic activity, like stilbenes. Exogenous and endogenous androgens can suppress the effects of these drugs, resulting in suspect or negative results. The detection of epithelial changes immunohistochemically with cytokeratin antibodies appeared to facilitate the diagnosis of hyperplasia and metaplasia in the prostate. A specific and sensitive method for detecting such lesions in formalin-fixed, paraffin-embedded prostate samples has been developed with the commercially available cytokeratin monoclonal antibody 34 beta E12, and applied to bulls treated with diethylstilbestrol-dipropionate. The highly reproducible staining pattern of 34 beta E12 can be used for the detection of hyperplasia and metaplasia in the prostate glands of animals treated illegally with oestrogens.

Animals↗
PubMed1996

Infectious and parasitic disease of captive reptiles and amphibians, with special emphasis on husbandry practices which prevent or promote diseases.

Reptiles and amphibians have been maintained in captivity for over one hundred years. The authors review the husbandry practices necessary for the optimal health of these species: for some species these are well known, while such information is lacking for other species. Infectious and parasitic diseases are presented in tabulated form, and a number of references are cited for those seeking more detailed information.

Amphibians↗
PubMed1995

Data compression of x-ray cardio-angiographic image series.

Medical x-ray images are increasingly stored and transmitted in a digital format. To reduce the required storage space and transmission bandwidth, data compression can be applied. In this paper we describe a new method for data compression of cardio-angiographic x-ray image series. The method is based on so-called overlapped-transform coding. A comparison with the well-known block-based transform-coding methods JPEG and MPEG is presented. We found that overlapped-transform coding does not introduce any blocking artefacts, in contrast to block-based transform coding, which introduces clearly visible blocking artefacts at compression ratios above 8. Clinical evaluations of the new method have pointed out that the image quality obtained at a compression ratio of 12 is adequate for diagnostic applications.

Angiocardiography↗
PubMed1994

Squamous metaplasia in the salivary glands of canaries (a case report).

Squamous metaplasia of the glandular epithelium was found in the palatine salivary glands of two canaries, originating from a flock in which there was a variable intake of egg food. The histological changes, in combination with the history, indicate a vitamin A deficiency as a result of a selective intake of food as the most likely aetiology.

Animal Feed↗
PubMed1994

P wave recognition and atrial stimulation with fractally iridium coated VDD single pass leads.

UNLABELLED: The bottleneck of VDD systems is the reliable detection of the small atrial signals by a floating atrial electrode. Fractally iridium coated electrodes offer excellent sensing and pacing performance. In this study, the performance of such a floating atrial lead in P wave sensing and synchronous ventricular stimulation was examined. Atrial pacing was also used as a test of atrial wall contact. PATIENTS AND METHODS: A fractally iridium coated VDD lead was implanted in 18 patients. In 15 patients it was interfaced with a VDD pacemaker and in 3 patients with a DDD system depending on the P wave amplitude measured acutely (> or = 2 mV). Simultaneous recordings of the surface ECG and pacemaker telemetry were used to analyze P wave amplitudes and AV synchrony in different body positions, and during normal and deep breathing. Additionally, exercise tests based on daily life activities and 24-hour ECG monitoring were performed to test the pacemaker function. RESULTS: During implantation P wave amplitudes were 1.86 mV +/- 1.08 mV (range 0.5-4.9 mV) and during follow-up (6.6 +/- 5.6 weeks) 0.18-3.8 mV. Holter recordings revealed reliable P wave sensing at a sensitivity setting of 0.5 mV (95.5%). P wave sensing was further improved by a higher atrial sensitivity. AV synchronous pacing > or = 99.9% was achieved in all patients. In 7 patients the atrial electrode could be positioned close to the atrial wall enabling atrial stimulation thresholds at an average of 4.3 volts. CONCLUSION: This fractally iridium coated VVD lead allowed consistent and reliable P wave sensing at an atrial sensitivity as low as 0.5 mV in selected patients.

Aged↗