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Biomedical subjects

P Bischoff

Publications and source records attributed to P Bischoff.

At least 19 recordsLinked to original sources
PubMed1995

[Clinical aspects of hypophyseal diseases from the viewpoint of the ophthalmologist].

The anatomy of the chiasmal region and the visual symptoms due to pituitary tumors will be presented from the viewpoint of an ophthalmologist. The importance of perimetry in every patient with otherwise unexplained loss of vision is stressed. Other tests (swinging flash light test, colour vision, screening ophthalmoscopy) are mentioned as well. An ophthalmologist should participate in the diagnosis as well as in the follow-up after treatment of any case with pituitary tumors.

Humans↗
PubMed1995

Long-term results of low vision rehabilitation in age-related macular degeneration.

One to five years after successful low vision rehabilitation, 199 patients with age-related macular degeneration were asked by means of a questionnaire whether they still used their low vision aids and whether they were satisfied with the low vision counseling. We received feedback from 66% of the patients. 20 patients had already passed away. 74% of the 112 answering patients still use a low vision aid today. Three-quarters of them still use the originally prescribed low vision aid. Interestingly enough, the daily reading time was rather short, only 16% of the patients read more than 1 hour per day, 42% read somewhat more and 13% somewhat less than 10 minutes per day. Retrospectively, 81% of all responding patients found their low vision counseling at least a little, more of them quite or very helpful. These numbers suggest, that the initial labor of patiently examining and training older, visually handicapped patients is worthwhile.

Aged↗
PubMed1995

Immunosuppressive activities of 6(5H)-phenanthridinone, a new poly(ADP-ribose)polymerase inhibitor.

6(5H)-phenanthridinone, a recently identified poly(ADP-ribose)polymerase (PARP) inhibitor, is able, at micromolar concentrations, to inhibit concanavalin A-induced lymphocyte proliferation and to potentiate the effect of gamma radiation upon murine spleen cells. When added at the onset of a mixed lymphocyte culture, this compound strongly depresses the induction of primary allogeneic (anti-H2k) cytotoxic T-lymphocytes (CTLs). Lymphokine-activated killer (LAK) induction was also found to be impaired by the PARP inhibitor. Taken together, these results clearly indicate that PARP plays a key-role in immune reactions involving cytotoxicity and that 6(5H)-phenanthridinone could be considered as a potent immunomodulator.

Acridines↗
PubMed1995

[Low dosage radiotherapy of subfoveal neovascularization in age-related macular degeneration. Preliminary results].

AIM OF THE STUDY: The aim of this study is to test the effect of low dose radiation on the subfoveal neovascular membranes (SNVM) and to analyse visual acuity in age-related macular degeneration. METHODS AND PATIENTS: From November 1993 through to August 1994, 10 patients, on the one hand, were given a dose of 5 Gy followed by controls 6 weeks and 6 months later. On the other hand, 21 patients were treated with a dose of 8 Gy and were subjected to controls 6 weeks later. Before the radiotherapy and during the control sessions, all patients were required to be measured for different parameters of visual acuity and to receive a simultaneous fluorescein and indocyanine green angiography. The radiotherapy was done by a linear accelerator 6 MeV and through a lateral port 3 x 4 cm in half beam technic. RESULTS: In the 5 Gy group, no changes in the parameters for visual acuity were noted in most cases after 6 months. In 9 of the cases, the membranes had increased in size and in 1 case, they had remained unchanged. In the 8 Gy group, no changes in the visual acuity or in the membrane size were diagnosed. Of all the patients treated, only one refused the angiography control. DISCUSSION AND CONCLUSIONS: Given the low dose used and the period of observation, the visual acuity of all patients remained stable. The size of the membranes increased in most cases for those 5 Gy patients and in this respect, no changes at all were noted in the 8 Gy patients. In order to better evaluate the potential of radiotherapy, this study must be pursued and coupled with further studies analysing the effect of different doses on patients.

Aged↗
PubMed1995

Microsatellite instability in adenocarcinomas of the upper gastrointestinal tract. Relation to clinicopathological data and family history.

We analyzed 66 adenocarcinomas arising in the upper gastrointestinal tract for microsatellite instability at eight microsatellite loci to investigate the role of these genetic alterations in the etiology of these tumors. We identified alterations in at least one locus in 11/46 adenocarcinomas of the stomach, in 2/15 adenocarcinomas arising in Barrett's esophagus, and in 1/5 adenocarcinomas of the duodenum and jejunum. Microsatellite instability in gastric tumors was found in 5/22 of intestinal, 1/3 of mixed, and 5/21 of diffuse type tumors. No relationship to the tumor stage (TNM), age, and survival time of the patients was observed. One patient had two synchronous gastric tumors both exhibiting microsatellite instability at multiple loci. His family history revealed four individuals in the maternal line afflicted with gastric carcinoma in three generations. Our data show that microsatellite instability is a genetic event in 11 to 24% of tumors of the upper gastrointestinal tract. The observation of microsatellite instability and a familial clustering of gastric tumors may suggest a genetic predisposition for a subset of gastric tumors, which may be identified by microsatellite analysis.

Adenocarcinoma↗
PubMed1994

Effect of 6(5H)-phenanthridinone, an inhibitor of poly(ADP-ribose) polymerase, on cultured tumor cells.

By catalyzing posttranslational modifications of nuclear proteins, poly(ADP-ribose) polymerase (PARP) controls their functions and therefore constitutes an enzyme of crucial importance in tumor development. In this study, we have investigated the action of 6(5H)-phenanthridinone, an isoquinoline derivative and one of the most potent PARP inhibitors described so far, on RDM4 murine lymphoma cells in culture. We also examined whether this compound could act synergistically with an antineoplastic drug in tumor-cell destruction. Our results demonstrate that a marked inhibition of PARP activity can be obtained in whole cells after a short incubation, and that this compound, when associated with an alkylating agent, dichloro-2,2' N-methyldiethylamine (chloromethine), leads to a marked drop in the RDM4 proliferation, indicative of a synergy between the two compounds.

Animals↗
PubMed1993

Apoptosis induced by oxysterols in murine lymphoma cells and in normal thymocytes.

Oxygenated derivatives of cholesterol (oxysterols), a family of naturally occurring compounds, possess marked anti-proliferative and immunosuppressive activities, in particular they have been shown to inhibit T-cell responses to different stimuli. 25-Hydroxycholesterol (25-OHC) and 7 beta,25-dihydroxycholesterol (7.25-OHC) are able to kill not only RDM4 murine lymphoma in vitro, but also, surprisingly, mouse thymocytes after several hours of incubation. In this study, we report that the death of RDM4 and thymocytes induced by oxysterols exhibits the features of apoptosis. This phenomenon was identified by agarose gel electrophoresis of DNA fragments extracted from the cells and quantified by flow cytometric analysis of the DNA fluorescence of propidium iodide-stained cells. Cycloheximide and actinomycin D were found to decrease the number of apoptotic cells and to increase cell viability, indicating a requirement for the synthesis of macromolecules in oxysterol-induced programmed cell death. The pathway by which 25-OHC and 7.25-OHC are able to induce apoptosis in this type of cell and the possible contribution of these compounds to thymus involution during development are discussed.

Animals↗
PubMed1992

Anti-(human LFA-1) monoclonal antibodies bind P815 murine tumour cells.

Using anti-CD11a and anti-CD18 monoclonal antibodies (mAbs) directed respectively against the alpha and the beta chains of LFA-1, we obtained an important and specific staining of P815 murine tumour cells. Both ascitic and cultured cells displayed a positive staining. Other murine tumours of haematopoietic origin, as well as lymphocytes or lymphoblasts from DBA/2 mice, were not labelled by the same monoclonal antibodies. These results were surprising since, to our knowledge, no case of cross-reaction between species has been reported with LFA-1. Moreover, competition assays showed that epitopes recognized by the two anti-CD11a antibodies were different from those identified by H35.89.9, a mAb raised against the murine LFA-1 alpha chain. Using allogeneic cytotoxic T lymphocytes, we also showed that anti-(human LFA-1) mAbs were unable to block the lysis of P815 by these effector cells. Thus, the putative functional properties of these structures, as well as their importance from an antigeneic point of view, remain to be assessed.

Animals↗
PubMed1992

Studies on the immunological effects of fatty alcohols--I. Effects of n-hexacosanol on murine macrophages in culture.

n-Hexacosanol (hexa), a long chain fatty alcohol extracted from Hygrophila erecta, has proved to possess neurotrophic activities on cultured neurons, and to attenuate the degeneration of cholinergic neurons after injury. In the present study, we show that hexa has also interesting properties on macrophages, a cell type largely represented in the brain: when added to mice resident peritoneal macrophages, it provokes significant morphological changes, and increases their phagocytosis capacity. These results may indicate that some membrane properties involved in these different effects and in macrophage functions are affected by n-hexacosanol, but other sites of action could also be considered.

Animals↗
PubMed1992

[Multicenter evaluation of a new local antihistaminic drug (levocabastine)].

The aim of this prospective, open study was to evaluate the efficacy and tolerance of the Levocabastine eye drops in daily practice. 273 patients with allergic (rhino)conjunctivitis were treated during 2 weeks. Objective findings and subjective assessments made by the patients were analyzed. The global efficacy was evaluated by the investigator as good or excellent in 73.8% (eye) and 53.6% (nose) of the patients. The results were not age-dependent. The tolerance was scored as good or excellent in 89% of the patients. Less than 6% of the patients stopped the treatment due to intolerance.

Adult↗
PubMed1992

Prolongation of survival in retrovirally induced T cell lymphoma by dietary omega 6 fatty acid.

C57BL/Ka mice were fed diets rich in omega 3 or omega 6 polyunsaturated fatty acids and inoculated with the thymic lymphoma-inducing retrovirus RadLV. Mice receiving the omega 3 diet died significantly sooner than those receiving the omega 6 diet. Of the three known mechanisms by which fatty acids can exert antiviral activity, namely, modification of membrane fluidity, modulation of immune response, and synthesis of metabolites with antiviral activity, the first two can be eliminated in the model under study. It is therefore concluded that differences in survival are due to fatty acid metabolites with distinct antiviral activities.

Animals↗
PubMed1992

[Ambulatory ophthalmologic surgery].

In the past years, more procedures (including intraocular surgery) have been performed on an outpatient basis, thanks to the added safety of microsurgery. The decision of whether to operate on an outpatient basis should not just be based on the kind of procedure but more on the patient's suitability and on his social context. The patient must be able to come daily to the office, and eye medication must be applied as prescribed by a relative or a neighbour.

Ambulatory Surgical Procedures↗
PubMed1991

Membrane-related oxysterol function: preliminary results on the modification of protein kinase C activity and substrate phosphorylation by 7 beta,25-dihydroxycholesterol.

Oxysterols exhibit a wide variety of biological activities, including potent immunosuppressive effects. 7 beta,25-Dihydroxycholesterol (7,25-OHC), a synthetic oxysterol, has been shown to strongly inhibit the lymphocyte response to different stimuli. This compound has been chosen as a model compound to investigate the mechanisms underlying the immunosuppressive effects of oxysterols. As protein kinase C (PKC) constitutes a key enzyme in the pathways leading to cell activation, we have studied the effect of 7,25-OHC on PKC activity in the cytosolic and particulate fractions of spleen cells. Lymphocytes treated with 7,25-OHC showed a decrease of the relative PKC activity in the particulate fractions compared to control cells. These results are confirmed by the observation that 7,25-OHC also reduces the phosphorylation of the endogenous PKC substrates. Thus oxysterols interfere with two membrane related phenomena, ie the modification of membrane PKC activity and the inhibition of the phosphorylation of the substrates of PKC located in the membrane. Previous results obtained by fluorescence polarisation revealed a modification of the membrane fluidity after oxysterol treatment. Furthermore, it has been demonstrated that oxysterols are incorporated into cell membranes. The alteration of the cell membrane could impair the signal transduction and may explain the immunosuppressive activity of oxysterol. Thus, along with other biological effects previously reported, oxysterols decrease membrane associated PKC activity in immune cells.

Animals↗
PubMed1991

[Diagnosis of optic neuropathy in endocrine orbitopathy].

By presenting the case of a patient with Graves-disease, different methods that permit detection of optic nerve compression are discussed. Beside reduced visual acuity and pathological visual fields, measurement of episcleral venous pressure, pathological visually-evoked potentials (VEP) and enlarged extraocular muscels (detected by CT and MRI) give good additional evidence of optic nerve compression in Graves-disease.

Diagnosis, Differential↗
PubMed1991

[Computer as replacement for the current medical record? Introduction of a pilot project of the St. Gallen ophthalmology clinic].

Computerized data processing is more and more used in hospitals and medical offices. There are no doubts about the usefulness of a computer for administrative tasks. At our Dept. of Ophthalmology we started a pilot project to enter the medical records into the computer. The pros and cons of such an information system are discussed. Entering medical records into the computer did not prove to be definite advantage for the physician.

Computer Systems↗
PubMed1990

[Sudden blindness].

Blindness means no light perception. In that case one observes a fixed dilated pupil. An unilateral amaurosis of sudden onset is caused either by an ocular or an optic nerve condition. The most common causes are: --occlusion of the central retinal artery --apoplexy of the papilla --traumatic lesions to the optic nerve Bilateral blindness occurring suddenly is for anatomic reasons due to a chiasmatic lesion. It is mainly associated with pituitary apoplexy. More commonly bilateral blindness develops sequentially and may be discovered only after the second event. Besides other ocular diseases bilateral occipital brain infarction has to be considered.

Acute Disease↗
PubMed1990

Monophosphoric acid diesters of 7 beta-hydroxycholesterol and of pyrimidine nucleosides as potential antitumor agents: synthesis and preliminary evaluation of antitumor activity.

7 beta-Hydroxycholesterol, which has been shown to be selectively cytotoxic toward tumor cells cultured in vitro, was converted into the corresponding water-soluble phosphoric acid ester and linked to a pyrimidine nucleoside such as 5-fluoro-2'-deoxyuridine or 2'-deoxyuridine. 2-Chlorophenyl phosphorodichloridate (3), without activation, was used directly to phosphorylate the protected oxygenated sterol. The intermediate phosphorylated the 5'-OH group of nucleoside selectively, leading to compounds 1a and 1b after deprotection. These compounds were screened for their antiproliferative activity toward EL-4 murine leukemia cells in vitro and for their antitumor activity against the mice bearing Krebs II ascitic carcinoma in vivo.

Animals↗