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Biomedical subjects

W Jansen

Publications and source records attributed to W Jansen.

At least 55 records · Page 3Linked to original sources
PubMed1991

Hyperthermia promotes the incidence of tumours following X-irradiation of the rat cervical cord region.

The cervical region of the rat, including the spinal cord (cervical 5-thoracic 2) was irradiated with single doses of 15-32 Gy 250 kV X-rays. Hyperthermia, at temperatures of 42-, 43- and 44 +/- 0.1 degrees C for 30 min was applied to the cervical vertebral column and immediate adjacent tissues for 5-10 min or 7 h after X-irradiation. Over a period of 18-21 months, animals were followed up to monitor neurological complications occurring as a result of damage to the spinal cord (Sminia et al. 1991). We also noted the development of neoplasms either inside or outside the cervical region. The data on tumour incidence were analysed retrospectively using the actuarial method. Although hyperthermia alone was not carcinogenic, it led to a significant increase of radiation-induced tumours. This increase of radiation carcinogenesis was observed both with hyperthermia applied 5-10 min after X-rays and with an interval of 7 h between X-rays and heat. Cancer induction was highest after the lower radiation doses (16 Gy) combined with high heat doses (30 min 44 degrees C). The latent period for induction of tumours by X-rays was 472 +/- 19 days (mean +/- SEM; n = 24). Latency was significantly shortened by hyperthermia to 404 +/- 34 days (n = 22) if applied 5-10 min after X-rays and to 348 +/- 6 days (n = 33) with an interval of 7 h. Histology revealed that 86% (38/44) of the examined tumours found inside the volume treated with hyperthermia and irradiation were sarcomas. The percentage of animals with a tumour outside the treated volume was almost the same for all treatment groups. Most of these tumours were of the mammary gland type.

Animals↗
PubMed1991

Effect of hydrogenase and mixed sulfate-reducing bacterial populations on the corrosion of steel.

The importance of hydrogenase activity to corrosion of steel was assessed by using mixed populations of sulfate-reducing bacteria isolated from corroded and noncorroded oil pipelines. Biofilms which developed on the steel studs contained detectable numbers of sulfate-reducing bacteria (10 increasing to 10/0.5 cm). However, the biofilm with active hydrogenase activity (i.e., corrosion pipeline organisms), as measured by a semiquantitative commercial kit, was associated with a significantly higher corrosion rate (7.79 mm/year) relative to noncorrosive biofilm (0.48 mm/year) with 10 sulfate-reducing bacteria per 0.5 cm but no measurable hydrogenase activity. The importance of hydrogenase and the microbial sulfate-reducing bacterial population making up the biofilm are discussed relative to biocorrosion.

Journal Article↗
PubMed1991

Slow release isosorbide-5-mononitrate therapy in angina pectoris. Effects of exercise performance and hemodynamics.

The possibility of maintaining preload reduction and enhancement of exercise tolerance during an interval treatment with 100 mg/day of slow-release isosorbide-5-mononitrate (IS-5-MN) was investigated in 12 patients (aged 57 +/- 5.0 years) with angiographically confirmed coronary artery disease and chronic stable angina pectoris. The effects of a single dose (acute test) were compared with those following an 8-day (chronic) regimen of mononitrate administration. Two hours after administration of 100 mg sustained-release IS-5-MN, mean resting pulmonary artery pressure (PAP), measured with a Swan-Ganz catheter, was reduced by 32% (p less than 0.001) and at submaximal exercise level (50 W, 3 min) by 37% (p less than 0.001). At individually highest comparable work loads mean PAP was reduced by 37% (p less than 0.001), and at maximal work load the PAP reduction was 14% (p less than 0.05). At the end of 1 week of therapy with sustained-release IS-5-MN a slight, clinically irrelevant reduction of hemodynamic effect was recorded. Work capacity increased after 1 h by 79% (264 +/- 154 vs. 472 +/- 180 W x min, p less than 0.01), still significantly above base-line 10 h after nitrate administration. No difference from baseline was demonstrable 24 h after medication. During interval therapy the improved work capacity was fully maintained (chronic, 1 h: 280 +/- 119 vs. 532 +/- 160 W x min, p less than 0.001). There was no significant difference between the plasma IS-5-MN levels at acute and chronic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Interval treatment of coronary artery disease with sustained-release isosorbide-5-mononitrate.

The possibility of maintaining preload reduction and enhancement of exercise tolerance during an interval treatment with 50 mg/day of sustained-release isosorbide-5-nitrate (IS-5-N) was investigated in 13 patients (aged 54.4 +/- 7.9 years [mean +/- standard deviation]) with angiographically confirmed coronary artery disease and chronic stable angina pectoris. The effects of a single dose (acute test) were compared with those following an 8-day (chronic) regimen of mononitrate administration. Two hours after administration of 50-mg sustained-release IS-5-N, mean resting pulmonary arterial pressure (PAP), measured with a Swan-Ganz catheter, was reduced by 27% (p less than 0.01), and at submaximal exercise level (50 W, 3 minutes) by 34% (p less than 0.001). At individually highest comparable work loads mean PAP was reduced by 28% (p less than 0.01), and at maximal work load the PAP reduction was 21% (p less than 0.05). At the end of 1 week of therapy with sustained-release IS-5-N a slight, clinically irrelevant reduction of hemodynamic effects was recorded. Work capacity increased after 1 hour by 60% (408 +/- 104 vs 653 +/- 147 W x min, p less than 0.001)--still significantly above baseline 10 hours after nitrate administration. No difference from baseline was demonstrable 24 hours after medication. During interval therapy the improved work capacity was fully maintained (chronic, 1 hour: 417 +/- 93 vs 679 +/- 160 W x min, p less than 0.001). During interval therapy with sustained-release IS-5-N, hemodynamics and exercise tolerance were durably improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Design of the diagnostic encyclopedia workstation (DEW).

The Diagnostic Encyclopedia Workstation (DEW) contains reference knowledge for diagnostic support in pathology. Illustrations are accessible via a video disc device. DEW can hold more knowledge, pictures and case histories than books, and its information is accessible via several entries. Software for data entry has been written in MUMPS with use of the relational database toolkit AIDA, which is particularly suited for manipulation of free text. The graphical mouse-driven user interface is written in C using MetaWindows. The DEW contains 85 diagnoses in ovarian pathology, covering all frequent cases and many rarities, illustrated by approximately 3000 pictures, divided among 158 cases.

Computer Systems↗
PubMed1990

Role of fructose-sorbitol malabsorption in the irritable bowel syndrome.

Because even after low doses of fructose and sorbitol, fructose-sorbitol malabsorption has been found in a high number of patients with the irritable bowel syndrome, an etiological role of fructose-sorbitol malabsorption in the irritable bowel syndrome has been suggested. However, these studies have been uncontrolled. Therefore, a controlled study of fructose-sorbitol malabsorption in the irritable bowel syndrome compared with healthy controls was performed. Seventy-three patients, 23 men and 50 women with a mean age 43.1 +/- 1.7 years (range, 18-66 years) with the irritable bowel syndrome were compared with 87 age- and sex-matched control subjects. Fructose-sorbitol malabsorption was determined by a breath-hydrogen test (Lactoscreen, Hoek Loos, Schiedam, The Netherlands) following an oral load of 25 g fructose and 5 g sorbitol after a 10-hour fast. Fructose-sorbitol malabsorption, as shown by an H2 peak of 20 ppm over basal values, was found in 22 (30.1%) of the patients and 35 (40.2%) of the control subjects. With a lower peak level of 10 ppm over basal values, these percentages were 45.2% and 57.5%, respectively. Also, the highest H2 peak values (15.2 +/- 2.3 ppm vs. 21.5 +/- 2.6 ppm), time to reach peak levels (110.7 +/- 5.4 min vs. 107.1 +/- 5.9 min), and area under the H2 curve (1310 +/- 219 ppm.min vs. 1812 +/- 255 ppm.min) did not discriminate between patients and controls. During the test, symptoms developed in 31 of 70 patients and in 3 of 85 control subjects (P less than 0.0001). Symptomatic patients did not differ from asymptomatic patients regarding the presence or absence of fructose-sorbitol malabsorption, H2 peak values, and area under the curve. No differences could be identified between male and female patients or controls. In conclusion, fructose-sorbitol malabsorption is frequently seen in patients with irritable bowel syndrome, but this is not different from observations in healthy volunteers. Therefore, fructose-sorbitol malabsorption does not seem to play an important role in the etiology of irritable bowel syndrome.

Adult↗
PubMed1990

Evaluation of a Diagnostic Encyclopedia Workstation for ovarian pathology.

The Diagnostic Encyclopedia Workstation (DEW) is a computer system that provides completely integrated pictorial and textual information as reference knowledge in the field of ovarian pathology. The textual component comprises information per diagnosis such as descriptions of macroscopic and microscopic images, clinical signs, and prognosis. In addition, the system offers lists of differential diagnoses and criteria to differentiate among lists of differential diagnoses and criteria to differentiate among them. The present study evaluates to what extent the system influences the diagnostic process in efficiency and outcome. Therefore, two groups of six pathologists each, covering a wide spectrum of experience in ovarian pathology, participated in the evaluation of the DEW. The quality of the resulting diagnoses was statistically analyzed with the Wilcoxon rank sum test with respect to five different viewpoints: classification, morphology, clinical consequences, duration of diagnostic process, and consensus among the participants. The results are discussed and it is concluded that classification and morphology showed better results when books were used. The evaluation experiment was, however, very rigid and negatively biased with respect to the DEW system. Positive aspects of the encyclopedia are the easy access to diagnostic and differential diagnostic information and the large set of illustrations. Insight is acquired with respect to existing bottlenecks and how they may be overcome.

Computer Systems↗
PubMed1990

Histopathological changes in the skin and subcutaneous tissues of mouse legs after treatment with hyperthermia.

The right hind legs of mice wee heated in a waterbath at 44 degrees C. The animals were killed at various time intervals after exposure. Tissue damage was studied histologically. After 15 min exposure light and reversible changes were seen including oedema and some neutrophilic inflammatory infiltration immediately after treatment. After 30 min exposure an extensive inflammatory infiltrate and strong oedema were seen during the first days after treatment. Adjacent to areas in the skin with strong oedema extensive muscular necrosis was observed. The muscular tissue regenerated almost completely in three weeks. After 60 min heating the histological picture was dominated by massive necrosis of muscle, subcutaneous fat tissue and skin during the first week after treatment followed by local ulceration. From about the 7th day after treatment regeneration of the epithelium started and granulation tissue could be observed in the margin of the ulceration. Healing of the skin was completed at about day 21 after treatment. Our results indicate that heat induced tissue damage in some tissues is due to a direct effect on the cells composing the tissue (e.g., fat cells in subcutaneous fat) but that, in most other tissues (e.g., muscle and skin) it is a consequence of damage to the vasculature.

Adipose Tissue↗
PubMed1990

Radiation enteritis: an overview.

The clinical and radiological findings in chronic radiation enteritis are described in a group of 18 patients. The patients presented with malabsorption, diarrhoea, chronic intermittent obstruction or a combination of these signs. Eventually all patients developed an ileus. The radiologist plays an important role in determining the cause of the clinical signs. The single-contrast barium infusion technique was used. In the jejunum no changes were found except bowel dilatation as a sign of an obstruction more distally. In the ileum there was evidence of submucosal thickening, adhesions and single or multiple stenoses. These changes are described in relation to the pathogenesis of chronic radiation enteritis.

Adult↗
PubMed1990

Incidence of tumours in the cervical region of the rat after treatment with radiation and hyperthermia.

The incidence of tumours in the irradiated cervical region in female Wistar (WU) rats after retreatment of part of the volume with hyperthermia was examined retrospectively. The cervical spinal cord (cervical 5-thoracic 2) was irradiated with a single dose of 15, 18 or 20 Gy. Ninety days thereafter, the cervical region was heated by means of a microwave applicator at a maximum temperature of 43 degrees C for 50-90 min measured at the vertebral column. Over a period of 18 months after treatment, animals were regularly observed. Neurological complications and the development of neoplasms were noted. From the 354 animals included in the study, 82 animals developed a tumour. Hyperthermia alone was not carcinogenic, but enhanced the carcinogenesis induced by radiation. The percentage of animals that developed a tumour inside the volume treated with hyperthermia 90 days after irradiation was significantly higher relative to radiation alone (33 +/- 5 per cent versus 4 +/- 2 per cent, P less than 0.001). The duration of the latent period before appearance of these tumours was not affected (355 +/- 18 days versus 425 +/- 54 days). No significant differences in the percentage of animals that developed a tumour at another site were observed between different treatment groups. Histology revealed that 88 per cent (14/16) of the examined tumours found inside the treated volume after hyperthermia and irradiation were soft tissue rhabdomyosarcomas. Outside the treated volume, most tumours were tumours of the mammary gland.

Animals↗
PubMed1990

Massive pleural effusion due to pancreatic pseudocyst.

Four patients with massive pleural effusions due to pancreatic pseudocysts who were initially treated conservatively with percutaneous pleural drainage are described. In two patients the pleural effusions and the pancreatic pseudocysts disappeared, but two required surgery, in one case because conservative treatment failed and in the other at a later date for a recurrent pancreatic pseudocyst.

Adult↗
PubMed1990

Pulmonary arterial pressure and working capacity as parameters for checking the development of tolerance under nitrate therapy.

Testing of the chronic therapeutic effects of antianginal drugs is commonly performed by stress electrocardiography. It is well known that this type of testing is easy to be disturbed by the influence of circadian rhythmus and placebo. However, by hemodynamic measurements such as the determination of pulmonary arterial pressure each patient can serve as his own control in therapeutic studies if the reproducibility of these parameters is acceptable. In 29 patients with coronary heart disease the reproducibility of the following parameters was tested at rest and during exercise and found to be acceptable: heart rate, mean arterial pressure, mean pulmonary arterial pressure, and working capacity. In additional studies the application of these parameters on the control of chronic therapy with antianginal drugs was performed. The results were: 1. A 1-week placebo treatment does not influence the parameters. 2. Long-term therapy with 3 x 20 mg of ISDN or IS-5-N daily over 4 weeks does not induce tolerance, whereas the dosage of 3 x 60 mg ISDN resp. 3 x 50 mg IS-5-N induces a remarkable degree of tolerance. 3. A 4-week therapy with 3 x 4 mg or 3 x 8 mg molsidomine daily resp. 4 mg or 8 mg molsidomine retard does not induce significant attenuation of the hemodynamic effects. 4. On a single-dose therapy with 50 mg IS-5-N retard ("interval-therapy") the therapeutic effects are maintained over at least 1 week.

Administration, Oral↗
PubMed1990

A method for the acquisition of formalized knowledge in pathology.

A tool is introduced for the acquisition of pathology knowledge in a formalized form, directly by the expert. Formalization of the knowledge is intended to make descriptive pathology knowledge more suitable for computerized diagnostic support since a formal representation of knowledge allows more extensive indexing, hence more flexible access. The knowledge acquisition (KA) tool also provides a useful research instrument to investigate to what extent pathology knowledge can be made explicit, to what degree ambiguity is present, in what way experts differ when formalizing knowledge, and whether it is feasible to incrementally acquire decision criteria on the basis of the formalized descriptive knowledge. Crucial in the design of the KA tool is the incorporated meta-knowledge, which is reflected by the knowledge-base structure and is used to elicit knowledge from the expert. Knowledge is acquired from the expert via a menu-driven user interface, which follows the general steps of the pathologist when describing a case. The paper discusses the considerations underlying the design, the implementation of the KA tool, and the research goals.

Diagnosis, Computer-Assisted↗
PubMed1989

A computer based handbook and atlas of pathology.

The Diagnostic Encyclopaedia Workstation (DEW) is a computerized handbook of pathology intended for use in diagnostic practice. It consists of a combination of a personal computer (PC), a video disc player (VDP), for which a specially developed disc is used, two monitors, a mouse and software. The hard disc of the computer contains textual information on diagnoses in categories such as macroscopy, common histology, immunopathology, clinical observations and prognosis and case histories. This information is frequently illustrated by pictures on a video disc which is automatically addressed by the computer software. All pictures, at present some 3000, pertain to case histories which are included in the system. Also integrated are classification aids in two categories: diagnostic criteria and differential diagnosis. Advantages of DEW over the use of conventional manuals are 1) the extensive volume of text, 2) the large number of high quality illustrations, 3) the immediate access to cross references and 4) the potential for continuous revision.

Anatomy, Artistic↗
PubMed1989

[Automated measurement of distance vision based on the DIN strategy].

A method for automated measurement of far vision is described which meets the test requirements laid down in the new DIN standards. The subject sits 5 m from a high-resolution monitor on which either Landolt rings or Snellen's types are generated by a computer. By moving a joystick the subject indicates to the computer whether he can see the critical detail (e.g., the direction of opening of the Landolt ring). Depending on the subject's input and the course of the test so far, the computer generates the next test symbol until the threshold criterion is reached. The sequence of presentation of the symbols and the threshold criterion are also in accordance with the DIN standard. Initial measurements of far vision using this automated system produced similar results to those obtained by conventional methods.

Distance Perception↗