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Biomedical subjects

J Schipper

Publications and source records attributed to J Schipper.

At least 145 records · Page 8Linked to original sources
PubMed1983

An accurate and simple method for megavoltage radiation therapy of retinoblastoma.

A simple but highly accurate irradiation method for the "conservative" treatment of retinoblastoma has been developed at the Utrecht Retinoblastoma Centre. Treatment is carried out with a 6 MV or 8 MV linear accelerator using a lateral D-shaped field of 26 X 32 mm2. This D-shaped field is specially contoured to include the entire retinal surface or vitreous and 10 mm of the anterior optic nerve and to protect the sensitive anterior structures of the eye, particularly the lens, as much as possible. Accurate positioning of the sharply collimated treatment field is easily done by magnetic fixation of the eye to the beam defining collimator by use of a low vacuum contact lens. As the fixed eye is located in the isocentre of the accelerator, the radiation beam can be directed at any angle by simple rotation of the gantry or table, without alteration of the position of the eye within the treatment field. Simultaneous irradiation of bilateral retinoblastoma is just as easily possible and can be done with the same accuracy by fixation of both eyes with contact lenses and alternately applying two opposing lateral fields. Prior to treatment, the axial dimensions of each eye are determined by ultrasonic biometry to ascertain the exact volume to be irradiated.

Anesthesia↗
PubMed1982

Effect of hypothalamus lesions on the presence of CRF-immunoreactive nerve terminals in the median eminence and on the pituitary-adrenal response to stress.

By use of an antiserum raised against conjugated ovine corticotropin releasing factor (CRF1-41), nerve fibres can be stained immunocytochemically in the external zone of the median eminence of rats. The presence of CRF-immunoreactive (CRFi) nerve fibres and the plasma corticosterone response to ether stress were studied in rats 6-7 days after making various types of lesions in the hypothalamus. Complete anterolateral deafferentation of the mediobasal hypothalamus caused complete disappearance of CRFi fibres from the median eminence and blocked the corticosterone response to stress. Incomplete anterolateral hypothalamic deafferentation did not prevent the stress-induced increase of corticosterone and in these rats, part of the CRFi nerve fibres remained intact. A horizontal cut placed ventral to the paraventricular nuclei, completely prevented the corticosterone response in those rats that showed a complete disappearance of CRFi nerve fibres from the median eminence. Some rats however, still exhibited CRFi nerve fibres and these animals responded to stress with increased corticosterone levels. A similar horizontal cut made just dorsal to the paraventricular nuclei affected neither the corticosterone response to stress nor the appearance of CRFi nerve fibres in the median eminence. We conclude that the presence of CRFi nerve fibres in the median eminence is a prerequisite for rats to show a pituitary-adrenal response to ether stress and therefore represents the first functional evidence for the role of these hypothalamic CRFi-neurons.

Adrenal Glands↗
PubMed1981

[Extracapsular cataract extraction combined with the implantation of an intraocular lens (author's transl)].

Between 1973 and 1980 349 intraocular lenses were implanted after intracapsular and 470 after extracapsular cataract operation. The results and complications are evaluated: following intracapsular lens extraction a 4-loop Binkhorst lens (iris clip lens) was inserted in all cases. Following extracapsular cataract operation a 2-loop Binkhorst lens (iridocapsular lens) was implanted in 194, a 4-loop lens in 276 cases. The two complications occurring most frequently were an Irvine-Gass syndrome in 10% following intracapsular, and a disturbing secondary cataract necessitating a discision in 19% after extracapsular lens extraction. A dislocation-decentration of the pseudophakos was observed in some cases after extracapsular cataract operation. It is therefore recommended that the extracapsular be preferred to the intracapsular cataract extraction, that a 4-loop lens be implanted, secured by a transiridectomy suture, but that the haptic part of the intraocular lens should not be inserted in the capsular bag. It is of paramount importance, especially in young pseudophakic patients, to prescribe carefully an additional optical correction, preferably progressive glasses.

Cataract Extraction↗
PubMed1980

A scanning microfluorimetric study on sympathetic nerve fibres: intraneuronal differences in noradrenaline turnover.

The quantitative aspects of formaldehyde induced fluorescence (FIF) of noradrenaline (NA) in sympathetic nerve fibres were studied in whole mount preparations of the iris of the rat. Both "static" and scanning microfluorimetric measurements showed a close linear relationship between the FIF intensity and the NA content after pharmacological treatment (alpha-methyl-p-tyrosine, amphetamine, guanethidine, nialamide). A histogram analysis method is described to study fluorescence changes in different parts of the nerve fibre histogram, in order to evaluate changes in different segments of the nerve fibres characterized by their fluorescence intensity. The method is illustrated by a study on NA turnover. The chemically determined halflife (T 1/2 of NA after alpha-methyl-p-tyrosine (4.3 h) was in close agreement with the T 1/2 estimated microfluorimetrically (4.2 h). However, pronounced differences were found in various parts of the nerve fibre histogram (3.7-6.3 h). We conclude that the turnover of NA is different in various segments of the sympathetic nerve fibres in the rat iris and that the most intensely fluorescent varicosities display the longest T 1/2 and the highest turnover rate of NA.

Adrenergic Fibers↗
PubMed1980

[Macular edema following implantation of Binkhorst lenses].

The incidence of cystoid mascular edema following intracapsular or extracapsular cataract extraction with implantation of a Binkhorst 4-loop lens is reported. The results, showing an incidence of macular edema of 13% after intracapsular operation and 2.1% after extracapsular operation, correlate well with reports published elsewhere. Most of the cases were recognized at the earliest three months after operation. A correlation with intraocular pressure was found. Examples of fluoresceinangiographic findings are presented.

Edema↗
PubMed1980

Microfluorimetric scanning of sympathetic nerve fibers: quantification of neuronal and extraneuronal fluorescence with the aid of histogram analysis.

A high resolution (0.5 micrometer), two-dimensional microfluorimetric scanning procedure was used to quantitate the formaldehyde-induced fluorescence of noradrenaline in the iris of the rat. Scanning of large areas (50 x 50 micrometer) in the sympathetic innervated dilator muscle revealed an overlap between measurements of nerve fibers and of background (smooth muscle). In order to discriminate between both populations, the scan data were converted into fluorescence histograms (256 fluorescence classes, and subjected to mathematical analysis. The characteristics of the background histogram were obtained from scans of iris preparations devoid of fluorescent nerve fibers (pretreatment of the donor rat with reserpine or sympathetic denervation). A curve-fitting program was applied on those fluorescence classes in the normal iris histogram that represent measurements on pure background and resulted in a full background histogram. After subtraction of this background histogram from the original histogram, a nerve fiber histogram was obtained. The validity of the algorithm was evaluated by scanning iris preparations with varying background intensities. The results showed that quantification of the nerve fiber fluorescence was independent of variation in the background.

Adrenergic Fibers↗
PubMed1979

On the presence of extraneuronal catecholamine in the iris of the rat: a scanning microfluorimetric study.

Formaldehyde-induced fluorescence (FIF) of noradrenalin (NA) was studied in histochemical preparations of the rat iris. With the aid of a two-dimensional microfluorimetric scanning method, quantitative information was obtained from neuronal and non-neuronal elements selectively. Spectral analysis and fluorimetric studies showed the existence of extraneuronal NA in the iris of untreated rats. Surgical and pharmacological (reserpine, amphetamine, imipramine, nialamide) manipulation of sympathetic neurotransmission-induced changes in extraneuronal fluorescence, which did not parallel changes in fluorescence of neuronal elements. A positive relationship was found between changes in extraneuronal fluorescence and the postsynaptic effect (pupil diameter). We hypothesize that extraneuronal catecholamine (CA) fluorescence is a histochemical parameter for synaptic neurotransmission.

Animals↗
PubMed1979

[A review of 400 intraocular lens implants (author's transl)].

400 intraocular lenses (iris-clip and iridocapsular pseudophakoi of the Binkhorst type) were implanted at the Lucerne Eye Hospital between 1973 and 1978. The present review emphasizes the paramount position of the ophthalmosurgeon among the complicating factors. The 2-loop metallic iridocapsular lenses were abandonned; secured iris-clip lenses are now after intra- and extra-capsular lens extraction. Aspiration of lens masses or needling of a secundary cataract were necessary in 27% of extracapsular lens extraction. Precipitates on the psuedophakoi were absent after intrakapsular lens extraction, indicating the uveitis being of phacogenic, not pseudophacogenic origin.

Cataract Extraction↗
PubMed1979

[Special indications, contraindications, particular methods of treatment in correction with intraocular lenses (author's transl)].

For the past 5 3/4 years intraocular lens implantion belongs to the routine operations performed in the Lucerne Eye Clinic. Whereas unilateral cataracts are the main and frequent indication for intraocular lens implants, there are certain cases of uni- and bilateral cataracts also, where the implantation of intraocular lens, due to its advantages, is specially indicated. Such cases are presented briefly in this paper. Good results are achieved through strictly observing the methods of treatment before and after the implantation of the lens.

Aphakia, Postcataract↗
PubMed1978

Microfluorimetric scanning of sympathetic nerve fibers. An improved method to quantitate formaldehyde induced fluorescence of biogenic amines.

A two dimensional scanning procedure was developed for studying quantitative aspects of formaldehyde induced fluorescence (FIF) from noradrenaline containing nerve fibers. A computer (PDP 12) controlled scanning device was equipped with a cooled photomultiplier, a 0.5 micron scanning stage and a 0.5 micron measuring spot. Photodecomposition was reduced by a high scanspeed (100/sec) and a small excitation field. Digitized images were obtained with a high resolution. Data (10,000/scan) of large scan areas (2500 micron2) in the iris of the rat were transformed into fluorescence histograms, which allowed statistical evaluation. Visible changes induced in the histochemical preparation by administration of drugs (reserpine, L-Dopa) were reflected in characteristic changes in the histograms. A minor reduction in noradrenaline content, which was too small to be detected by visual observation of the microscopical image and by classical microfluorimetric methods, did evoke a significant change in the histograms. It is concluded that microfluorimetric scanning is a very sensitive technique for detecting changes of formaldehyde induced fluorescence from neuronal networks.

Adrenergic Fibers↗
PubMed1978

[On the correction of posttraumatic unilateral aphakia in children and in adults with artificial intraocular lens implants (author's transl)].

The problems of optical correction of unilateral traumatic aphakia are discussed. The treatment of choice is a combined Cataract-operation with intraocular lens implants. The operation must be done as soon as the eye is free of inflammation. Prescription of bifocal glasses in addition to pseudophakoi is necessary. With this method a "malignant" Strabismus can be avoided and binocular vision, stereopsis as well as minimal grade of aniseikonia can be achieved.

Adolescent↗
PubMed1978

[Early results with scleral flap by Preziosi's operation (author's transl)].

The antiglaucomatous Preziosi operation leads within some months in a relatively high percentage of cases to a cataract necessary operation. The main cause for the seems to be a flat anterior chamber lasting several days. Posterior synechaie are frequent. Two out of 55 patients developed an infection of the filtration bleb. By additional preparation of a scleral flap over the sclerectomy complications were obviously rarer, and the regulation of the pressure was very good. There was no difference if the operation was done with or without scleral flap. High pressures during the first days after operation normalize themselves spontaneously or by massage of the eye ball, and have no significance the prognosis. In the cases with scleral flap the filtration blebs show good vascularisation, only in a few cases we saw cystic areas without vessels within filtration blebs with good vascularisation. Moreover the anterior chamber is formed much quicker and complications such as cataract are rare.

Cataract↗