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Biomedical subjects

J Schipper

Publications and source records attributed to J Schipper.

At least 127 records · Page 7Linked to original sources

Attributional cognitions, coping behavior, and self-esteem in inpatients with severe spinal cord injuries.

The purpose of this study was to examine the relation between attributional cognitions, coping behavior, and self-esteem of inpatients with severe spinal cord injuries. Thirty inpatients from rehabilitation centers were interviewed. Their coping behavior was assessed by a physician, a nurse, and a psychologist. The results showed sometimes different tendencies for the recently vs. long-disabled patients with respect to the direction of the relation between attributional cognitions and rehabilitation outcome (coping behavior and self-esteem). Especially noteworthy is the evident adaptiveness in the group of the long-disabled inpatients with regard to being concerned with the causes of the accident and being concerned with the avoidability of the accident that led to the injury, while in the recently disabled group these cognitions are related to nonadaptiveness. To be concerned with the question, "Why did this have to occur to me?" was strongly related for the long-disabled inpatients with poor coping behavior, while this was not the case for the recently disabled.

Adaptation, Psychological↗

Non-corresponding radiological and surgical diagnoses in patients operated for sciatica.

One hundred and nine patients with radicular leg-pain underwent both computer-tomography and myelography and were subsequently operated upon. The diagnoses on computer-tomogram, myelogram and surgery failed to correspond in 41 cases. Stenosis of the bony spinal canal, scar formation, and an intra- or extraforaminal herniation were the most frequent causes of discrepancy in the diagnoses. In cases of spinal stenosis and previous disc surgery both computer-tomography and myelography have to be performed. Certain precautions taken during computer-tomography and myelography may reduce the number of discrepant findings.

Adolescent↗

Protective effect of hypoxia in the ram testis during single and split-dose X-irradiation.

Spermatogonial stem-cell survival in the ram was studied after single (6 Gy) and split-dose (2 x 3 Gy, interval 21-24 h) X-irradiation both under normal and hypoxic conditions. Hypoxia was induced by inflation of an occluder implanted around the testicular artery. The occluders were inflated about 10 min before irradiation and deflated immediately after. Stem-cell survival was measured at 5 or 7 weeks after irradiation by determination of the Repopulation Index (RI) in histological testis sections. The RI-values after fractionated irradiation were only half those after single dose irradiation. Hypoxia had a protective effect on the stem-cell survival. After split-dose irradiation under hypoxic conditions two times more stem cells survived than under normal oxic conditions; the RI-values increased from 34% (oxic) to 68% (hypoxic). This effect of hypoxia was also found after single dose irradiation where the RI-values increased from 68% (oxic) to 84% (hypoxic). The development of the epithelium in repopulated tubules was also studied. Under hypoxia, a significantly higher fraction of tubules with complete epithelium was found after single (38 vs. 4%) as well as after split-dose irradiation (12 vs. 0%).

Animals↗

D2-dopamine receptors regulate the release of [3H]dopamine in rat basal hypothalamus and neurointermediate lobe of the pituitary gland.

Homogenates of the rat basal hypothalamus and the neurointermediate lobe of the pituitary gland contained relatively high levels of dopamine as was estimated by high-performance liquid chromatography (HPLC). The release of [3H]dopamine was studied in these regions and desipramine was used to prevent uptake of [3H]dopamine in noradrenergic nerve terminals. The release of radioactivity could be stimulated electrically and was calcium-dependent. It appeared that the release of radioactivity could be inhibited by drugs stimulating D2-dopamine receptors in both regions. The radioactivity released during electrical stimulation was analysed by cation exchange chromatography and appeared to consist predominantly of [3H]dopamine. It is our conclusion that D2-receptors mediate the inhibition of the release of [3H]dopamine from dopaminergic nerve terminals in the basal hypothalamus and in the neurointermediate lobe.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

Single cell quantitative immunocytochemistry of cyclic GMP in the superior cervical ganglion of the rat.

In the superior cervical ganglion of the rat, using a newly developed antiserum against formaldehyde-fixed 3',5'-cyclic guanosine monophosphate (cGMP), cGMP immunoreactivity was observed in the large postganglionic neuronal cell bodies; no cGMP-immunofluorescence was found in nuclei or in satellite cells, glia or fibroblasts. In vitro incubation of ganglia in media with high K+ (up to 100 mM) or carbachol (10(-8)-10(-5) M) showed an increase only in cGMP-immunofluorescence in the large postganglionic cell bodies. The intensity of the immunofluorescence was taken as a measure for cGMP-immunoreactivity and was quantitated using a Leitz MPV-II system. Dose-response curves were constructed for the increase in cGMP-immunofluorescence intensity for K+ and carbachol. The carbachol stimulated cGMP-immunofluorescence intensity was antagonized competitively by atropine, whereas the high K+ stimulated cGMP-immunofluorescence intensity was not. Hexamethonium (10(-6) M) was without effect on the carbachol stimulated cGMP-immunofluorescence intensity. The morphological and pharmacological data indicate that we developed a very specific procedure for quantitative immunocytochemistry of cGMP in tissue sections. This technique makes it possible to use cGMP-immunofluorescence intensity as a postsynaptic parameter in individual cell bodies in heterogeneous tissue.

Animals↗

D-2 dopamine-receptors regulate the release of [3H]dopamine in rat cortical regions showing dopamine immunoreactive fibers.

Using an antibody raised against dopamine the occurrence of dopamine-containing fibers was demonstrated in the prefrontal cortex, anterior cingulate cortex, parietal neocortex, piriform cortex and entorhinal cortex. In extracts of these cortical regions significant amounts of dopamine, although approximately a 100-fold less than in the neostriatum or nucleus accumbens, were detected with high performance liquid chromatography. The release of [3H]dopamine from slices of all these cortical regions was studied in vitro in a superfusion system and desipramine was used to prevent the uptake of [3H]dopamine in noradrenergic nerve terminals. It appeared that the electrically evoked release of radioactivity was inhibited by drugs stimulating D-2 dopamine-receptors in all the regions studied. Cation-exchange column chromatography revealed that the radioactivity released consisted predominantly of [3H]dopamine, indicating that D-2 receptors mediate the inhibition of the release of [3H]dopamine from dopaminergic nerve terminals. Likewise, in the neostriatum as well as in the nucleus accumbens D-2 receptor stimulation inhibits the release of [3H]dopamine. Therefore it is our conclusion that D-2 receptors regulate the release of dopamine from dopaminergic neurons originating in the ventral tegmental area as well as in the substantia nigra.

Animals↗

A new approach to immunocytochemistry of 3',5'-cyclic guanosine monophosphate: preparation, specificity, and initial application of a new antiserum against formaldehyde-fixed 3',5'-cyclic guanosine monophosphate.

The development of a new 3',5'-cyclic guanosine monophosphate (cGMP) antiserum was initiated starting from the following considerations: (a) adequate fixation of cGMP is a prerequisite for a reliable demonstration of soluble cGMP, and (b) fixation might influence the specificity of the immunocytochemical demonstration of cGMP. Therefore, cGMP-protein conjugate was prepared in a way which equals tissue fixation. cGMP was coupled to bovine thyroglobulin using formaldehyde. Antibodies against this conjugate were raised in rabbits. The specificity of the antisera was evaluated in a gelatin model system. No immunoreactivity was observed with nucleotides other than cGMP or with rabbit preimmune sera. Immunoinhibition experiments showed that only the cGMP-formaldehyde-thyroglobulin conjugate and, to a lesser extent free cGMP, absorbed onto the antiserum. In rat brain an extensive localization of cGMP-immunostaining was found. Examples are hippocampus CAI and CAII, and cortical layers II and V. No cGMP-immunostaining was found in the cerebellum. In vitro incubated superior cervical ganglia showed cGMP-immunostaining in the large postganglionic neuronal cell bodies; this cGMP-immunostaining increased upon incubation of the ganglia in iso-osmolar 100 mM K+. In conclusion, we prepared a new-type highly specific antiserum against cGMP, suitable to demonstrate cGMP-immunoreactivity in tissue material.

Animals↗

Lumbar disk herniation: diagnosis with CT or myelography.

The value of computed tomography (CT) and myelography as single investigations in the diagnostic evaluation of patients with radiating leg pain probably due to lumbar disk herniation (LDH) has been adequately demonstrated. However, the extent to which CT can replace myelography and the conditions in which the examinations should be combined and in which order are still uncertain. Results of CT scans and myelograms from 461 patients with symptoms of lumbar root compression, probably due to LDH, were evaluated and compared with surgical results, if available. The sensitivity of myelography exceeded that of CT (82% vs. 73%), but its specificity was lower (67% vs. 77%). The positive predictive value of myelography only slightly differed from that of CT (93% vs. 94%). These results were used to establish a sequential diagnostic workup for patients with radiating leg pain. If, in this population with a high prior probability for surgery, CT had been the investigation of first choice in patients suspected of having LDH, the number of myelographic procedures performed could have been reduced by two-thirds.

Adult↗

Biochemical effects in rats after acute and long-term treatment with clovoxamine.

Clovoxamine, a nontricyclic antidepressant, has a dual action in blocking the reuptake of both noradrenaline and serotonin. Acute in vitro receptor binding studies showed that clovoxamine has little affinity for muscarinic, histaminergic, serotonergic and adrenergic binding sites. After chronic administration, clovoxamine induced a decrease in the functional beta-adrenergic receptor coupled c-AMP response. A comparison made between clovoxamine (with a very short half life value in rats) and desipramine indicated that the decrease in the beta-receptor coupled c-AMP response was similar, regardless whether the compounds were injected i.p. twice daily (10 mg/kg) or delivered via an osmotic minipump (20 mg/kg/day) for 21 days. Chronic administration of both clovoxamine and desipramine by twice daily i.p. injections or osmotic minipumps in rats resulted also in a down regulation of the number of 5-HT2 receptors in frontal cortex. The alteration in beta-receptor number (Bmax) did not correlate with the decrease in adenylate cyclase activity. These data support a multistep process of the down regulation of the beta-adrenergic system in which the first step is the uncoupling of the receptors resulting in a decrease in the agonist-stimulated adenylate cyclase without necessarily a change in Bmax. The observed biochemical effects in rats after acute and chronic administration with clovoxamine further support the antidepressant activity of this compound.

Animals↗

Corticotropin-releasing factor immunostaining in the rat spinal cord and medulla oblongata: an unexpected form of cross-reactivity with substance P.

By use of two antisera (alpha-CRFA, alpha-CRFB) raised against conjugates of o-CRF and bovine thyroglobulin, cryostat sections of formaldehyde-fixed gelatin models containing o-CRF can be stained. The staining intensity was quantitated by use of an automated microfluorimeter and was shown to be dependent on the concentration of o-CRF (1-300 microM) added to the gel. Determination of the CRF staining intensity after incorporation of o-CRF-related peptides and fragments indicated that both antisera reacted with the C-terminal region of o-CRF. They showed poor cross reactivity with r-CRF fixed in the gel. In the same models, r-CRF could be immunostained efficiently by use of an antiserum (alpha-CRFC) raised to a conjugate of r-CRF and thyroglobulin. This antiserum reacted with the N-terminal and midportion parts but not with the C-terminal fragment of o-CRF fixed in the gels. By use of both o-CRF antisera nerve fibers can be stained in the rat hypothalamus (median eminence) and in the medulla oblongata (spinal trigeminal tract and nucleus) and spinal cord (dorsal horn). Immunoinhibition experiments showed that o-CRF caused a concentration-dependent quenching (0.001-1 microM) of the immunostaining of o-CRF-containing models, rat median eminence and medulla oblongata preparations. alpha-CRFC also stained CRF immunoreactive (CRFi) fibers in the rat hypothalamus with an equal distribution to that found with the o-CRF antisera. However, no immunostaining was found in the spinal trigeminal nucleus and tract and in the dorsal horn, indicating that these fibers store different CRF-related products from those found in the hypothalamus. The CRFi in the medulla oblongata and spinal cord induced by alpha-CRFA was completely abolished 1 week after treatment of adult rats with capsaicin, a substance known to deplete Substance P (SP) from those areas. Gels incorporated with SP showed a concentration-dependent increase (range 10-1000 microM) in immunostaining with both o-CRF sera but not with the r-CRF antiserum. In addition, incubation of o-CRF sera with SP caused a concentration-dependent quenching (range 10-100 microM) of immunostaining in SP-containing models. SP at a concentration of 100 microM was also effective in quenching the CRFi in the dorsal horn and spinal trigeminal area. Quenching was also obtained with the C-terminal part of o-CRF (range 0.002-0.1 microM), which indicates that both CRF antisera contain an immunoglobulin which recognizes determinants on CRF as well as on SP.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

Treatment of retinoblastoma by precision megavoltage radiation therapy.

The principal treatment concept in the Utrecht Retinoblastoma Centre is megavoltage irradiation, followed by light coagulation and/or cryotherapy if there is any doubt as to whether the residual tumour is still active. Radiation therapy is administered by means of a simple but highly accurate temporal beam technique. A standardized dose of 45 Gy is given in 15 fractions of 3 Gy at 3 fractions per week. From 1971 to 1982, 39 children with retinoblastoma have been irradiated in at least one eye. Of the 73 affected eyes, 18 were primarily enucleated, one received light coagulation only, and 54 received radiation therapy. Of the 54 irradiated eyes, 32 were additionally treated by light coagulation and/or cryotherapy for suspicious residual tumour (in 29 eyes), recurrent tumour (in 1 eye), and/or new tumour (in 3 eyes) and 10 were ultimately enucleated. Two eyes also received hyperthermia. The percentages of cure of the irradiated eyes with a minimum follow-up of 2 years were 100% (14/14), 100% (9/9), 83% (10/12), 79% (11/14) and 0% (0/5) in the Reese-Ellsworth groups I to V-A, respectively. Of the saved eyes 95% achieved useful vision. Eighteen eyes developed a clinically detectable radiation cataract; in five of these the lens was aspirated. Cataracts developed exclusively in those lenses of which a posterior portion of more than 1 mm had to be included in the treatment field. The likelihood and the degree of cataract formation was found to be directly related to the dose of radiation to the germinative zone of the lens epithelium. The minimum cataractogenic dose found in this series was 8 Gy.

Cataract↗

[Iatrogenic teflon granuloma of the eyelid. (Teflon paste, an unsuitable filling material for plastic eyelid surgery)].

A paste of granular Teflon was injected into the upper lid of a patient for remodeling the upper palpebral furrow, which had been retracted by scars. Large foreign-body granulomas developed a few weeks later, necessitating two excisions. The causes of this unsatisfactory result with a filling material which is well established in laryngeal surgery are discussed. The authors advise against using it in well vascularized loose tissue.

Adult↗

Quantitative immunocytochemistry of corticotropin-releasing factor (CRF). Studies on nonbiological models and on hypothalamic tissues of rats after hypophysectomy, adrenalectomy and dexamethasone treatment.

Indirect immunofluorescence cytochemistry of ovine corticotropin releasing factor (oCRF) was performed by use of an antiserum raised against a conjugate of oCRF and bovine thyroglobulin. The staining intensity was quantitated by use of an automated microfluorimeter. In cryostat sections of formaldehyde fixed oCRF containing gelatine models, the staining intensity was dependent on the concentration of oCRF (1-100 microM) added to the gel. Immunoinhibition experiments showed that oCRF induced identical concentration-dependent (0.001-1 microM) quenching of the immunostaining of oCRF containing models and rat median eminence (ME) preparations. Comparison of immunoinhibition of oCRF and ME extracts indicates that approximately 1.5 ng of CRF immunoreactivity (CRFi) is present in the ME of intact adult male Wistar rats. In the hypothalamus of rats, the majority of CRFi nerve fibers are localized in the external zone of the median eminence, whereas a large population of CRFi cell bodies is present in the paraventricular nucleus. Manipulations of the pituitary-adrenal system result in changes in the distribution of CRFi in these neurons. One week after extirpation of the adrenals or of the pituitary gland, the CRFi in the ME was reduced to 32 +/- 3% and 48 +/- 6% respectively. This decrease in CRFi in the median eminence can be largely prevented by treatment of rats with dexamethasone in doses that effectively reduce plasma ACTH and corticosterone levels. In contrast to intact rats, CRFi cell bodies can be visualized in the paraventricular nucleus of non-colchicine-treated rats after adrenalectomy or hypophysectomy. These data support the view that the hypothalamic CRFi neurons play a central role in the control of pituitary-adrenal activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗

A three-dimensional description of heating patterns in vascularised tissues during hyperthermic treatment.

A three-dimensional finite difference computer model has been developed to calculate temperature distributions in vascularised tissues in hyperthermia. Besides offering the possibility of calculating temperature distributions according to the conventional ' bioheat transfer' method, this model allows the introduction of several discrete blood vessels and can describe their influence on the temperature distribution. The model can be used to evaluate all types of heating techniques. First calculations on discrete large vessels show inhomogeneities caused by these vessels in the temperature distribution in tissue in hyperthermia. The theory and model presented can form the basis of a new bioheat transfer theory, with a vessel-temperature related bioheat transfer heat-sink term able to describe the small-scale temperature variation problems in local hyperthermia.

Blood Vessels↗

Mapping of CRF-immunoreactive nerve fibers in the medulla oblongata and spinal cord of the rat.

By use of an antiserum raised against Corticotropin Releasing Factor (CRF 1-41), nerve fibers can be stained in the medulla oblongata and spinal cord of rats. A dense plexus of CRF-immunoreactive (CRFi) nerve fibers is present in the nucleus tractus spinalis nervi trigemini from which fiber bundles enter the tractus spinalis nervi trigemini. Large numbers of CRFi fibers are present in the substantia gelatinosa of the spinal cord, while the tractus solitarius, the nucleus tractus solitarius and the nucleus ambiguus contain a low number of CRFi fibers. In rats treated with colchicine, CRFi cell bodies are found in the hypothalamus and occasionally in the nucleus tractus solitarius and the nucleus olivaris inferior. Posterolateral deafferentation of the hypothalamus did not result in a disappearance of the CRFi fibers in the medulla oblongata and spinal cord 7 days after surgery. These results indicate that CRFi fibers present in the spinal cord and medulla oblongata are part of a novel peptidergic neuronal system, which is different from the hypothalamo-infundibular CRF system.

Animals↗