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Biomedical subjects

R Steiner

Publications and source records attributed to R Steiner.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Modified radiation administration in Er:YAG laser ab externo sclerostomy].

BACKGROUND: Ab externo sclerostomy enables the restrained aqueous humour drain via a microgram wide corneoscleral canal into the subconjunctival space being an alternative surgical method in glaucoma therapy. The tissue ablative infrared laser radiation (2.94 microgram) was applied until now via a quartz fiber manually pushed forward in permanent tissue contact. Our aim was the development of a new applicator tip without manual feed in order to achieve a reduction in times for construction and maintenance of the former tip as well as in the risk of an infection and mechanical damage of intraocular structures. MATERIAL AND METHOD: In pig eye experiments, the laser parameters were varied in histological and scanning electron microscopic evaluation (pulse energy: 10-60 mJ, repetition rate: 5-17.5 Hz, combinations of constant power: 200 mW). Their influence on the canal shape and the morphology of the internal ostium has been proven in special tests. RESULTS: The new development of the applicator tip (core diameter: 550 microgram) enables a conical profile of the beam (diameter 500-150 microgram) within a distance of 2-3 mm, now without pushing the fiber forward ("fixed fiber"). Smooth canal surfaces, a small homogeneous necrosis zone (25 microgram) and only few tissue ruptures have been seen histologically and on SEM. The correlations of ablation rates/-speed as well as canal characteristics are more significant to energy densities than to repetition rates. First clinical application was technically successful. CONCLUSIONS: The new applicator tip optimizes the method of Er: YAG-laser ab externo sclerostomy from the technical and surgical point of view.

Animals↗
PubMed1997

Energy transfer spectroscopy for measuring mitochondrial metabolism in living cells.

Microscopic energy transfer spectroscopy was established using mixed solutions of reduced nicotinamide adenine dinucleotide (NADH) and the mitochondrial marker rhodamine 123 (R123). This method was applied to probe mitochondrial malfunction of cultivated endothelial cells from calf aorta incubated with various inhibitors of specific enzyme complexes of the respiratory chain. Autofluorescence of the coenzyme NADH as well as energy transfer efficacy from excited NADH molecules (energy donor) to R123 (energy acceptor) were measured by time-gated fluorescence spectroscopy. Because intermolecular distances in the nanometer range are required for radiationless energy transfer, this method is suitable to probe selectively mitochondrial NADH. Autofluorescence of endothelial cells usually exhibited a weak increase after specific inhibition of enzyme complexes of the respiratory chain. In contrast, pronounced and statistically significant changes of energy transfer efficacy were observed after inhibition of the same enzyme complexes. Detection of NADH and R123 in different nanosecond time gates following the exciting laser pulses enhances the selectivity and improves quantification of fluorescence measurements. Therefore, time-gated energy transfer spectroscopy is suggested to be an appropriate tool for probing mitochondrial malfunction.

Animals↗
PubMed1997

Nonlinear dynamics of intracellular methylene blue during light activation of cell cultures.

Methylene blue (MB+) is a well-known dye in medicine and has been discussed as an easily applicable drug for topical treatment in photodynamic therapy (PDT). Methylene blue can potentially be used as a redox indicator to detect the important redox reactions that are induced during PDT. The kinetics of this process was analyzed on a subcellular level with confocal laser scanning microscopy. BKEz-7 endothelial cells were incubated 4 h with 1 microM MB+. The fluorescence dynamics of MB+ during irradiation with 633 nm light was observed with subcellular resolution. Images were acquired at 0.5 s intervals (frame rate 1 image/0.5 s). Fluorescence was observed in the red channel of the laser scanning microscope. Synchronously, the phase-contrast image was visualized with the green channel. Morphological changes could therefore be correlated with the dynamics of MB+. In addition, the light-dose-dependent phototoxicity at 633 nm irradiation was determined by viable cell counting. After an induction period (phase I), fast fluorescent spikes could be observed in the whole cytoplasm, which decayed with a time constant of about 20 s (phase II), followed by a period of nearly constant fluorescence intensity (phase III) and exponential photobleaching (phase IV). Phase II exhibits highly nonlinear kinetics, which is hypothesized to correlate probably with a nonlinear quantal production of reactive oxygen species (ROS). Morphological cell changes were not observed during phase II. During phase III, a pycnotic cell nucleus developed. From the determination of viable cells we can conclude that a light dose applied within phase II was only sublethal in correlation with morphological observations. Overproduction of ROS leading finally to cell killing during phases III and IV is discussed.

Animals↗
PubMed1997

[Cervical pregnancy. A gynecologic-obstetric emergency situation].

The cervical pregnancy is defined as the implantation of the blastocyst into the cervical canal. The characteristic clinical sign is a severe asymptomatic uterine bleeding in early pregnancy or during curettage. Prior to 1978, correct preoperative diagnosis was rare and in almost all cases a hysterectomy was performed. Today, transvaginal sonography allows early diagnosis, and conservative treatment (two-time treatment: first treatment with systemic or intraamniotic methotrexate, secondly with curettage or ligature of the uterine arteries) improves the prospects of fertility.

Abortion, Induced↗
PubMed1996

Are coping strategies related to disease outcome in early breast cancer?

A consecutive series of 107 women with early breast cancer were investigated for coping strategies and disease outcome 5 to 6 years after primary surgical treatment (mastectomy or lumpectomy). Coping was assessed several times during a 3-year investigation period by the Zurich and Freiburg Questionnaires of Coping with Illness (ZQCI, FQCI). Data analysis revealed no significant correlations between coping strategies and the target variable "death from breast cancer". However, significant relations were found between postsurgical tumour size (p < or = 0.01), positive histological node status (p < or = 0.01) and death from breast cancer. The results of a discriminant analysis also indicated that somatic parameters are more important for the course of breast cancer disease than psychological aspects of coping. The role of psychosocial variables for the outcome of cancer disease remains unclear and further studies in this field are necessary.

Adaptation, Psychological↗
PubMed1996

Dynamic fluorescence changes during photodynamic therapy in vivo and in vitro of hydrophilic A1(III) phthalocyanine tetrasulphonate and lipophilic Zn(II) phthalocyanine administered in liposomes.

The fluorescence emission of hydrophilic tetrasulphonated aluminium phthalocyanine (AlPcS4) and hydrophobic zinc phthalocyanine (ZnPc), bound to the membrane of liposomes, was investigated in vivo in an appropriate tumour model of the rat bladder and in RR 1022 epithelial cells of the rat. The sensitizers were administered systemically to the rats and photodynamic therapy (PDT) was performed 24 h later. During PDT treatment, the fluorescence was measured every 30 s. The fluorescence was excited with 633 nm light from an HeNe laser and the fluorescence spectra were detected with an optical multichannel analyser system. PDT was performed for both sensitizers using 672 nm light from an Ar+ dye laser. The fluorescence changes during PDT were significantly different for the two phthalocyanines. For AlPcS4, an initial fluorescence intensity increase, followed by subsequent photobleaching, was observed. In contrast, ZnPc fluorescence showed an exponential decrease and no increase at the start of treatment. Tumour necrosis 24 h after PDT was significant only for ZnPc. RR 1022 cells incubated for 24 h with AlPcS4 revealed a granular fluorescence pattern, whereas ZnPc was localized diffusely in the cytoplasm of the cells. In agreement with the in vivo measurements, subcellular relocalization and a fluorescence intensity increase were detected exclusively in the case of AlPcS4. Morphological changes at this time were significant only for ZnPc. The subcellular localization and fluorescence kinetics were obtained using a confocal laser scanning microscope.

Animals↗
PubMed1996

[Concomitant injuries after upper ankle joint dislocations].

Functional treatment with the Air Stirrup Ankle Brace recommended by C. N. Stover in 1979 can reduce pathological inversion of the ankle joint. In our retrospective study of 109 patients treated by this kind of ankle brace we found 96 patients (88%) with excellent results. Only 13 patients (12%) reported moderate to good results. To detect and characterize their painful conditions of ankles we did a clinical, radiological and MRI-Investigation. In only 2 cases we found a moderate instability after clinical investigation, anterior stress roentgenogram and talar tilt. By using the MRI-investigation 1.0 Tesla with a 512 x 360 Matrix we could find 10 cases with osteochondral lesions of the ankle. In 7 cases there was separated ossicle in the fibulotalar joint, in 1 case we detected a fracture of the processus anterior tali, in another case we could see a posttraumatic lesion of the talus and calcaneus with bone bruise and at least one osteochondral fracture of the distal tibia. The capability of the MRI to detect particularly osteo-chondral lesions of the talus and the tibiofibular joint was shown in 10 of 13 cases. Therefore we recommend to do an MRI-investigation on all patients after ankle sprain if there are painful conditions within the ankle after conservative treatment.

Adult↗
PubMed1996

[Ab externo sclerostomy with the Er:YAG laser: report of outcome after 2 years].

OBJECT: Results over a period of 24 months of performing the Er:YAG laser ab externo sclerostomy. MATERIAL AND METHODS: The procedure was performed 81 times (chronic glaucoma with open angle (n = 55) and narrow angle (n = 15), 6 secondary glaucoma, 4 pigment glaucoma, 1 normal pressure glaucoma) in 74 eyes of 64 patients at the age of 70 +/- 10 years without any peribulbar anesthesia. The pulse energy was 11 mJ with a repetition rate of 7 Hz. Antimetabolites were not applicated. Success was defined as an IOP of less than 22 mm Hg or a decrease of at least 30%, with or without anti-glaucoma medication. RESULTS: The mean IOP of all cases decreased from preoperatively 28 +/- 8.1 mm Hg (Success group: 26.7 +/- 7.3 mm Hg) to 15 +/- 8.4 mm Hg (Success group: 14.6 +/- 7.8 mm Hg) on the first postoperative day. The success rate was about 50% within the period of two weeks to six months and decreased to about 15% in the 24th month. Complications were iris incarceration/synechia (n = 33), hypotony (n = 36) with consequent choroidal detachment (n = 8), hyphema (n = 19) and more pronounced inflammation symptoms (n = 10). In most cases, the early postoperative outflow failure is caused by iris incarceration into the internal ostium. The scarring tendency of the episcleral tissue leads to closure of the external ostium after months. Resurgery was necessary in 26 cases. CONCLUSIONS: Further efforts should be directed to maintain the intact corneoscleral morphology of the canal, created by an optimized method of the surgical technique. The application of antimetabolites in correct dosage or the implantation of modified silicon draining systems would be helpful.

Aged↗
PubMed1996

Regeneration processes in rabbit endometrium: a photodynamic therapy model.

The origin and process of regeneration in rabbit endometrium was evaluated following photodynamic epithelial destruction using topically applied aminolevulinic acid (ALA). Selective destruction of endometrial epithelium was performed using photodynamic therapy (PDT). ALA was diluted to 200 mg/ml dextran 70 shortly prior to administration. A volume of 1.2 ml was injected into the left uterus. Intrauterine illumination (wavelength 630 nm, light dose 40-80 J/cm2) was performed 3 h after drug administration. Tissue morphology was evaluated by light and scanning electron microscopy 1, 3, 7 and 28 days post-treatment (three animals at each time-point). Regeneration of the endometrium following epithelial ablation by PDT was fully activated after 24 h and was completed after 72 h. Endometrial surface generation occurred by proliferation, originating primarily in deeper regions of the glands. Findings from our morphological follow-up study support the origin of endometrial regeneration being mainly from undifferentiated stem cells and residual glandular epithelium.

Aminolevulinic Acid↗
PubMed1996

Immunoglobulin E response to human proteins in atopic patients.

The demonstration that human IgE recognizes both exogenous allergens and structurally related human proteins has led to the hypothesis that IgE autoreactivity may be a pathogenic factor in atopic diseases. To determine the frequency of occurrence as well as the disease specificity of this phenomenon, we tested sera from patients with atopic diseases and, for control purposes, from persons with immunologically mediated disorders for serum IgE reactivity with nitrocellulose-blotted human proteins. We found that 12 of 20 sera from atopic patients with pronounced skin lesions contained Western blot-detectable IgE antibodies. Patients suffering predominantly from allergic rhinoconjunctivitis as well as control individuals failed to display serum IgE autoreactivity, but occasionally exhibited elevated serum IgE levels. The molecular weights of the IgE-defined autoantigens ranged predominantly from 10 to 100 kDa. Whereas some of these were expressed in only certain cell types, others were detected in histogenetically different cells. Our results suggest that IgE autoimmunity occurs frequently in atopic dermatitis patients and may be of pathogenic relevance for the chronicity of skin manifestations typical of this disease.

Antibody Specificity↗
PubMed1995

Nonallergic individuals recognize the same T cell epitopes of Bet v 1, the major birch pollen allergen, as atopic patients.

The immune response toward allergens in nonallergic healthy individuals was investigated. To boost immune responses, two injections of birch pollen extract were administered to five nonallergic volunteers. T cell lines (TCL) with specificity for Bet v 1, the major birch pollen allergen, were established and analyzed for epitope specificity using overlapping peptides. Forty-nine T cell clones (TCC) specific for Bet v 1 were isolated from TCLs. Comparison with TCL and TCC established from birch pollen-allergic patients was performed. All TCC revealed the Th phenotype. Epitope specificities of TCL and TCC from nonatopics were identical to those found in allergic individuals. No association between MHC class II molecules and particular epitopes could be observed. In nonallergic as well as in allergic individuals, cytokine production in response to specific stimulation revealed a majority of Th-clones producing IL-4 and IFN-gamma. However, TCC derived from atopic individuals revealed a higher IL-4/IFN-gamma ratio. Immunoblot and ELISA revealed Bet v 1-specific IgG in nonallergic individuals before and after booster injections, but no IgE could be detected. High levels of Bet v 1-specific IgG and IgE could be detected in birch pollen-allergic patients. It can be concluded, that nonatopic and allergic individuals display the same repertoire of T cell specificities. In allergic individuals, the activation of allergen-specific TCC leads to a higher ratio of produced IL-4 vs IFN-gamma, which is responsible for enhanced IgE production.

Allergens↗
PubMed1995

An investigation of differences between three age groups in verbal and spatial task performance using the dual-task paradigm.

A dual-task paradigm with concurrent verbal and spatial tasks was used to investigate differences across three age groups for lateralized effects, magnitude of tapping interference, and cognitive task output. In addition, rescaled scores comparing verbal with spatial measures within and across age groups were analyzed to examine asymmetric age differences for right versus left hemisphere abilities. Results of the present dual task finger tapping investigation of three age groups showed all groups left lateralized for verbal tasks and right lateralized for spatial tasks. However, the magnitude of interference in tapping was significantly greater in paced nonideational shadowing tasks and during paced purposeful spatial tasks. Outcomes of exploratory analyses suggest a complex interplay between aptitude and the corresponding lateralized effects and cognitive effort to perform the task.

Adolescent↗
PubMed1995

Intracellular fluorescence behaviour of meso-tetra(4-sulphonatophenyl)porphyrin during photodynamic treatment at various growth phases of cultured cells.

Meso-tetra(4-sulphonatophenyl)porphyrin (TPPS4) taken up by cells is mainly localized in lysosomes as previously shown by fluorescence microscopical and fluorescence spectroscopical investigations. In the present study the intracellular fluorescence behaviour and the intracellular amount of this dye at various growth periods of cells were examined. For cells irradiated in the growth phase a relocalization of TPPS4 from the lysosomes into the cytoplasm and finally into the nucleus was observed. In contrast, for cells irradiated in the stationary phase no redistribution could be detected and therefore no evidence for severe damage of the lysosomal membranes and subsequently for the release of lytical enzymes is given. In both cases lethal damage of the cells was achieved as examined using the trypan blue exclusion test. This indicates that damage of the lysosomes is less important in the photodynamic inactivation of cells sensitized by TPPS4.

Animals↗