PubMed Health⌕ Search

Biomedical subjects

P Zwart

Publications and source records attributed to P Zwart.

At least 19 recordsLinked to original sources
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↗
PubMed1994

[Training in wild animal science in Europe].

A review of curricular and non-curricular teaching of European veterinary students is given. Diseases of exotic animals and birds are usually taught separately. Many countries teach about diseases of fishes; the most intensive training programmes seem to be in Norway and Spain. The teaching programmes reflect the increase and diversification in veterinary science as well as the interest and demands of the public in the various countries.

Animals↗
PubMed1992

Changing cytokeratin expression patterns in diethylstilbestrol dipropionate-induced metaplastic lesions of the goat prostate.

Five-month-old male goats were treated with 25 mg diethylstilbestrol dipropionate (DES-DP) by a single intramuscular injection, causing characteristic histological alterations in the peripheral glandular epithelium of the prostate, resulting in squamous metaplasia. Using a panel of monoclonal and polyclonal cytokeratin antibodies on frozen tissue sections of control prostates, we were able to immunohistochemically distinguish between the normal secretory cells, which are positive for cytokeratin 18 as detected with the antibody RGE 53, and the scattered basal cells, which could be specifically stained by the antibody RCK 103. Cytokeratins indicating squamous differentiation, i.e., nos 4 and 13, recognised by the antibodies 6B10 and 1C7, respectively, were found in sporadic cells throughout the normal goat prostate. Profound changes in cytokeratin expression were observed in the metaplastic lesions as compared to control peripheral glandular tissue. In this respect three monoclonal antibodies are of special interest. RCK 103 is immunoreactive with resting and all stages of differentiating basal cells. Antibodies 1C7 and 6B10 strongly stain the squamous cells in the metaplastic lesions, with 1C7 staining all the squamous cells in the lesions except the basal cell layer, and 6B10 being immunoreactive with the same suprabasal cells or the more differentiated cells in the upper strata. As a result the number of cytokeratin 18-positive cells is drastically reduced upon metaplasia. The results indicate that the goat system can be used as a suitable model system to further test the applicability of immunohistochemical methods in meat inspection and toxicological pathology.

Animals↗
PubMed1992

Quantification of percutaneous absorption of metronidazole and levamisole in the fire-bellied toad (Bombina orientalis).

Spot-on application has proved to be an effective way to reach therapeutic doses of metronidazole and levamisole in fire-bellied toads. The percutaneous absorption of metronidazole and levamisole was quantified, using an aqueous solution of 1.008 mg/ml of metronidazole and an aqueous solution of 3.767 mg/ml of levamisole. High Performance Liquid Chromatography (HPLC) analysis of the percutaneous absorption revealed that of the amount applied, 75% of metronidazole and 90% of levamisole was absorbed. This resulted during 3 days of application in dosages of 23 mg/kg BW of metronidazole and 94 mg/kg BW of levamisole. Of the absorbed substances, 48% of metronidazole and 9% of levamisole were excreted in urine and faeces as unmetabolised substances.

Administration, Cutaneous↗
PubMed1991

[Comparative pathology; territory with many streams].

Normal and abnormal situations in the reptilian ovary are reviewed. The normal development of the ovary is mainly governed by the temperature and variations in length of daylight. Vitellogenesis, (the production of yolk) takes place in the liver and is regulated by oestrogens. Under an abnormal light regimen, for instance 12 hours of light--12 hours of darkness, erratic vitellogenesis may occur. Atresia or resorption of follicles may occur at all stages of their development. The pathology of the process of resorption is characterised by the invasion of blood vessels and phagocytosis of yolk by macrophages. Pseudopregnancy is referred to for the first time. An important pathological aspect is the sterile inflammation of the ovary, which is fairly common in reptiles. The pathogenesis most probably is a trauma or some other defect of the egg membrane, resulting in leakage of vitelline into the surrounding fatty tissues. This contact gives rise to a chronic granulomatous inflammation. Comparative pathology covers a very wide field. In the Department of Special Animal Pathology, the specialization known in other areas of the veterinary profession, is directed towards a concentration of staff members on certain groups of animals such as mammals, birds, reptiles and laboratory animals respectively. At thesis was advanced, stating that a problem-solving attitude of the students cannot be solely attained by participation of veterinary students in fundamental research. The department of veterinary pathology is devoted to a problem-solving mode of education of students.

Animals↗
PubMed1989

[Triploidy in the newborn infant; clinical course and cytogenetic aspects].

Two female newborns with multiple malformations who survived for 7 days and 6 1/2 hours, respectively, had the symptoms and cytogenetic aspects of triploidy (69,XXX). Autopsy showed that the gallbladder was absent in both. Until now only ten patients who lived for more than 24 hours have been described. According to probability calculus, approximately 17 patients with triploidy should be born each year in the Netherlands; the chance of having a child with triploidy in the next pregnancy is almost nil. This emphasizes the importance of chromosomal analysis in stillborns or liveborns with complex abnormalities.

Abnormalities, Multiple↗
PubMed1989

[The humane killing of fishes, amphibia, reptiles and birds].

Methods, whether or not acceptable in the correct killing of fish, amphibians, reptiles or birds, are reviewed. The acceptable or unacceptable character of each of these techniques is commented upon. The techniques are differentiated into mechanical, chemical and physical methods. Of all mechanical techniques, rendering an animal unconscious by a sharp blow on the head, followed by rapid decapitation is an acceptable method. Of the chemical techniques, inhalation of Halothane, CO2 + O2, or ether, are usually acceptable. Cutaneous absorption by bathing in a solution of the anaesthetic tricaine sulphonate (MS 222) is the method of choice in fish and amphibians. The injectable anaesthetics T61 and pentobarbital-Na are acceptable in all groups of animals. Physical techniques such as supercooling, heating or electrocution are either unacceptable or impracticable in veterinary practice. Attention is paid to the effects of each of these techniques on the animal, the executing individual and the owner. Technical details of the methods most preferable in the humane killing of animals are discussed.

Amphibians↗
PubMed1989

Diseases in zoo animals.

A survey was presented on diseases in zoo animals, with special emphasis on artiodactylids. Both diseases of the organs as well as infectious diseases were enlightened. The importance of pure-breeding of species and subspecies among antelopes was illustrated by the results of chromosome-analysis in cases revealing poor development of the testicles and/or aspermiogenesis. These features were especially present in crossbreds. Materials existed of animals originating from zoological gardens and in some cases from the wild, which either were abnormal, diseased or had died.

Animals↗
PubMed1989

Prolapsus vaginae in the IIIVO/JU rabbit.

In a specified pathogen free (SPF) breeding colony of IIIVO/JU rabbits 8 cases of prolapsus vaginae occurred in 5 years. Clinically the animals were in shock. Haematocrits ranged from 9 to 15%. The prolapses started from the submucosal layer of the proximal part of the vestibulum vaginae. The prolapsed tissue consisted of over-expanded blood-sinuses. Between the sinuses signs of an inflammatory reaction were present. All 8 animals were in a period of increasing sexual activity when the prolapse developed. The 8 rabbits were closely related, indicating a possible hereditary defect.

Animals↗