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Biomedical subjects

H J Wagner

Publications and source records attributed to H J Wagner.

At least 91 records · Page 5Linked to original sources
PubMed1996

Rod outer segment renewal in the retinae of deep-sea fish.

Outer segment renewal involves the synthesis of disc material in the photoreceptor inner segments, the shedding of the tips of the photoreceptor outer segments, and their phagocytosis by the retinal pigment epithelial cells. It has been suggested that in the retinae of deep-sea fish no renewal of outer segments may take place. In order to assess outer segment renewal in deep-sea fish retinae we counted (i) periciliary vesicles in rod inner segments as a parameter for disc-synthesis activity and (ii) phagosomes in retinal pigment epithelial cells as a parameter of shedding and phagocytosis in 12 species of deep-sea fish with multibank or single bank retinae. We also measured the lengths of rod outer segments in order to evaluate the balance between synthesis and phagocytotic activity. In four of these species (Synaphobranchus kaupi, Nematonurus armatus, Coryphaenoides guentheri and Halosauropsis macrochir) we further recorded size-related changes of these parameters and their relation to the position of a given rod within the banks in the retina. The number of periciliary vesicles was highest in inner segments of the most vitread bank and in the periphery of the retina. Phagosomes were most abundant in retinal pigment epithelial cells of the central retina. Long rod outer segments were most frequently recorded in the peripheral retina indicating that in this region new synthesis may outbalance shedding. Vitread rod outer segments were only slightly longer than sclerad ones. Larger animals had shorter rod outer segments than small ones. We present evidence that rod outer segment renewal takes place in the retina of all deep-sea fish. Vitread rods may be more active in this respect than sclerad ones.

Animals↗
PubMed1996

Intra-vitreal injection of substance P antibodies as an antagonist in the vertebrate (fish) retina.

A method is described for using substance P (SP) antibodies as an antagonist in the retina of a cyprinid fish, the roach (Rutilus rutilus). Antibody solution (10 microliters) injected into the vitreous was found by immunohistochemical localization to penetrate the neural retina up to the level of the inner margin of the inner nuclear layer. Thus, the inner plexiform layer, where SP would normally be released, was well infiltrated. Similar penetration patterns were observed 2 or 24 h after injection. The physiological effectiveness of the antibody was demonstrated indirectly by measuring its effect upon the spatial coupling of the horizontal cells. Previous work suggested that SP stimulates dopamine release which normally uncouples the horizontal cell somata but not the syncytium of their axon terminals. In retinae isolated from antibody-injected eyes, the horizontal cell somata (but not axon terminals) were indeed found to be significantly more strongly coupled, consistent with the blockage of SP-induced, presumably tonic, release of dopamine. The results suggest that peptide antisera can be useful as pharmacological tools to investigate electrophysiological effects of neuropeptides in the retina as in other parts of the central nervous system.

Animals↗
PubMed1996

Horizontal cell spinule dynamics in fish are affected by rearing in monochromatic light.

Blue acaras (Aequidens pulcher, Cichlidae) were reared for 1 yr in white or monochromatic "red", "green" and "blue" lights to study the function and control mechanisms of horizontal cell (HC) spinules in the synaptic pedicles of cones. Ratios of spinules per synaptic ribbon (S/R) were determined in tangential sections in both single and double cones. We found that the S/R ratios in light adapted retinae decreased with decreasing wavelength of the rearing light in all cone types. Conversely, there was an increasing number of incompletely formed spinules with the highest frequency in the blue light group. Dark adaptation resulted in the complete degradation of mature spinules. However, significant numbers of incompletely degraded spinules were observed in the group reared in blue light. Fish reared in blue light which were transferred to white light formed mature spinules when light adapted and still had vestigial spinules when dark adapted. The mechanisms of spinule formation and degradation and the control of spinule dynamics appear to be fully developed in fish reared in monochromatic light. However, long-term chromatic deprivation seems to induce a compensatory modulation of spinule dynamics. A working hypothesis is formulated that interprets the observed effects as manifestations of differences in the activition of dopaminergic interplexiform cells (light adapted) and the sensitivity to glutamate of HCs (dark adapted). Our findings are consistent with the hypothesis that spinules are involved in sign-inverting feedback transmission from HCs to cones.

Adaptation, Ocular↗
PubMed1996

Adaptation-dependent changes of bipolar cell terminals in fish retina: effects on overall morphology and spinule formation in Ma and Mb cells.

We have investigated the effects of light and dark adaptation on the overall morphology of bipolar cell (BC) terminals in sublaminae a and b of the inner plexiform layer after labelling with Lucifer Yellow (LY) and PKC immunostaining using confocal laser scanning microscopy and serially sectioned material for electron microscopy. Three-dimensional reconstructed terminals showed marked adaptation-dependent changes of their morphology. Terminals of mixed rod-cone BCs in sublamina a (Ma BC) were irregular and scalloped in light adapted, but smooth and regular in dark-adapted specimens. Terminals from mixed rod-cone BCs in sublamina b (Mb BCs) exhibited an opposite behaviour. At the ultrastructural level, bipolar terminals in both sublaminae showed fingerlike extensions (spinules) invaginating presynaptic amacrine cell (AC) processes. Sixty-two percent of the dark-adapted Mb terminals in sublamina b showed spinules, whereas 21% of the light-adapted terminals had spinules. By contrast, 50.6% of the light-adapted Ma terminals in sublamina a formed spinules, compared to 17.8% of the dark-adapted Ma terminals in this sublamina. These observations reflect the functional subdivision of the inner plexiform layer in an inner ON-and an outer OFF-centre lamina. Our findings suggest that the synaptic plasticity of BC axon terminals may be due to differences of BC membrane potential, or the activity of AC input onto bipolar terminals. They may contribute to processes of fine tuning regulating the efficiency of AC-BC interaction under varying adaptation conditions.

Adaptation, Ocular↗
PubMed1996

Immunologic properties of Epstein-Barr virus-seronegative adults.

Epstein-Barr virus (EBV) seronegativity is rare in people > 20 years old. However, some persons remain EBV-seronegative for nearly their whole lives. The aim of this study was to examine properties of the immune system of EBV-seronegative adults that could contribute to long-term EBV seronegativity. Therefore, differential blood cell counts and lymphocyte subpopulations were determined, and the production of interferon (INF)-alpha and -gamma and interleukin (IL)-6 and -2 in a whole blood assay was investigated. Whereas no differences in the distribution of lymphocyte subpopulations between EBV-seronegative and -positive adults were found, a significant higher percentage of monocytes in EBV-seronegative adults was observed. Significantly more IFN-alpha and IL-6 were detected in culture supernatants of EBV-seronegative persons after stimulation with Newcastle disease virus. In contrast, no differences in the induction of the lymphokines IFN-gamma and IL-2 were seen. These data suggest that faster and higher production of IFN-alpha and IL-6 amy protect EBV-seronegative adults against EBV infection.

Adult↗
PubMed1996

[Special treatment methods in general practice--legal medicine viewpoint].

There is only one common medical law which is valid for all physicians. No therapy method can claim a special status or special rights. However, due to the considerable differences in training and qualification, the jurisdiction grants special rights to a healer without medical exam (non-medical practitioner) in comparison to a physician. Additionally, a physician has to take into account the limitations by the social legislation when he uses "special treatment methods" to avoid claims for compensation.

Complementary Therapies↗
PubMed1995

Differentiation of photoreceptors, glia, and neurons in the retina of the cichlid fish Aequidens pulcher; an immunocytochemical study.

Light-microscopic immunocytochemistry was carried out to investigate the developmental dynamics of several neurochemical markers in the retina of blue acara (Aequidens pulcher). As a rule, double-label experiments were performed in order to determine the absolute and relative timing of the appearance of these markers. The diameter of eye-ball (from 0.6 to 1.2 mm) and the body length (from 4.6 to 9.4 mm) enlarged in parallel during the observation period of 2 to 9 days after spawning (day 2-9); hatching took place usually on day 2. Immunoreactive proliferating cell nuclear antigen (ir-PCNA) was present in all neuroblasts (the embryonic homogeneous cell stage; day 1.0-2.0), but was lost progressively in a center-to-periphery and apparent proximal-to-distal sequence as the cells and layers differentiated. In late larvae and juveniles, ir-PCNA was confined to a ring of dividing neuroblasts at the retinal margin and to a population of scattered rod precursors in the outer nuclear layer. Immunoreactive structures of representative antigens progressively appeared after ir-PCNA had decayed. Around hatching, at the synaptic separation stage (day 2.0-2.5), luteinizing hormone-releasing hormone-ir centrifugal fibers, visinin-ir cones, glial fibrillary acidic protein-ir structures and gamma-aminobutyric acid-ir cell bodies appeared, which were followed by the emergence of rhodopsin-ir rods and tyrosine hydroxylase-ir interplexiform cells (on day 2.5-3.0) and serotonin-, neuropeptide Y- and substance P-ir amacrine cells (on day 3.0-4.0). The results indicate that photoreceptor cells, and especially rods start to differentiate at an earlier stage of retinogenesis than has previously been proposed. In addition, an extraretinal tissue in the brain identified as the prospective pineal organ was found to be visinin- and rhodopsin-immunoreactive on day 1.5-2.0 before these photoreceptor-specific antigens became positive in the retina.

Animals↗
PubMed1995

Coincidence of Epstein-Barr virus reactivation, cytomegalovirus infection, and rejection episodes in renal transplant recipients.

Reactivation of the Epstein-Barr virus was reported to occur frequently under immunosuppressive therapy following organ transplantation. However, little is known about the clinical significance of these EBV reactivations. Therefore, we searched for correlations among the treatment with various immunosuppressive drugs, the incidence of CMV infections, rejection crises, and serological signs of EBV reactivation. EBV-specific antibodies were measured with novel ELISAs, utilizing the recombinant antigens p72 (for anti-EBV nuclear antigen [EBNA]1-IgG), p54, and p138 (anti-early antigen [EA]-IgM, -IgG, -IgA) in a follow-up study of 79 renal transplant recipients. Patients receiving antithymocyte globulin or antilymphocyte globulin therapy showed increasing anti-EA-IgG and -IgA more often than did patients not receiving antithymocyte globulin or antilymphocyte globulin therapy (P < 0.05). In patients receiving OKT3 antirejection therapy, anti-EA-IgM seroconversion was found more frequently (P < 0.01). A significant correlation was also found between groups of patients who had had at least one rejection episode versus patients without any sign of organ rejection, and the incidence of increasing anti-EA-IgG (P < 0.05). Since in most of these patients signs of EBV reactivation followed the appearance of the rejection episode, this may not be due to viral-induced rejection but may be caused by the reinforced immunosuppression during antirejection therapy. As opposed to patients with no signs of CMV infection and with nonsymptomatic CMV infection, patients undergoing symptomatic CMV infection showed anti-EA-IgM seroconversion (P < 0.01), increasing anti-EA-IgA (P < 0.01), and decreasing anti-EBNA-IgG (P < 0.01) more frequently. Our results confirm the role of immunosuppressive therapy in the pathogenesis of EBV reactivation. We further demonstrate a striking coincidence of EBV reactivation and symptomatic CMV infection.

Antibodies, Viral↗
PubMed1995

[Iatrogenic esophageal perforation in inoperable esophageal carcinoma. Its therapy with a plastic-coated metal stent].

A 60-year-old man was admitted to hospital because of severely impaired swallowing, retrosternal pain and marked weight loss. History and physical examination of the patient, whose general condition was obviously much reduced, pointed to carcinoma of the oesophagus. Contrast-medium swallow demonstrated subtotal stenosis in the oesophagus. Computed tomography and magnetic resonance imaging showed a space-occupying mass originating from the oesophagus, in close relationship to the trachea, main bronchi and descending aorta. Biopsy confirmed the diagnosis of oesophagus carcinoma and exploratory thoracotomy excluded curative surgical treatment. An attempt was made to introduce a feeding tube endoscopically to provide nutritional palliation. But the oesophagus was perforated during this manoeuvre and resulted in an oesophagobronchial fistula with subsequent mediastinitis and mediastinal emphysema. Using a self-expandable plastic-covered metal stent it was possible to cover the perforation and overcome the patient's dysphagia. The mediastinitis healed under intravenous administration of cefotaxim (2 g three times daily), netilmicin (400 mg daily) and metronidazole (500 mg three times daily), for 5 days.

Carcinoma, Squamous Cell↗
PubMed1995

[Percutaneous intraluminal ultrasound studies of the biliary tract in the diagnosis of malignant biliary obstruction].

The diagnostic value of percutaneous intraluminal ultrasound examination of the biliary tract (PIBUS) for the staging of malignancies that had obstructed the biliary tract was assessed in a prospective study. Intrabiliary sonography was performed 25 times in 22 patients (seven women, 15 men; mean age 66.4 +/- 16 years) with obstructive jaundice in whom percutaneous transhepatic drainage of the biliary tract had been undertaken. The obstruction involved the hepatic duct bifurcation in 15 patients, the distal portion of the choledochal duct in five and its central portion as well as hepaticojejunostomy in one patient each. Ultrasound examination made it possible to assess tumour infiltration into the lumen of the biliary tract, its wall or its surrounding structures. Correct T-staging was successful in all 12 patients with carcinoma of the biliary tract (T1: n = 4; T2: n = 2; T3: n = 6), judged against the "gold standard" of exploratory laparotomy in nine. Infiltration of the portal vein was demonstrated in three patients, lymph node metastases in the region of the hepatoduodenal ligament in seven. This experience indicates that PIBUS makes it possible correctly to T-stage carcinoma of the biliary tract, but because of its limited depth penetration it has to be combined with conventional imaging procedures for precise definition of the N and M stages.

Aged↗
PubMed1995

Mammalian Müller (glial) cells express functional D2 dopamine receptors.

Dopamine plays important functional roles in the vertebrate retina. Here we show that functional D2 dopamine receptors are present on mammalian retinal Müller (glial) cells. Using an antiserum directed to two oligopeptides predicted from rat D2 receptor DNA, patchy label was demonstrated immunocytochemically on virtually all Müller cells enzymatically isolated from guinea-pig and rat retinae. Application of exogeneous dopamine to voltage-clamped isolated living guinea-pig Müller cells caused either a decrease (40%), an increase (32%), or no change (28%) of the input resistance of the membrane. The D2 receptor agonist quinelorane caused an increase of the membrane's input resistance in 100% of the cells. This effect was completely blocked by the D2 receptor antagonist S(-)-sulpiride. When all voltage-activated K+ channels except the delayed rectifiers were blocked by Ba2+, quinelorane had no effect. Further, the reversal potentials of the responses were near the potassium equilibrium potential. We conclude that the activation of Müller cell D2 receptors closes (inwardly rectifying) K+ channels. The presence of functional dopamine receptors on mammalian Müller cells may have important consequences for retinal K+ clearance, and thus, for information processing in the retina.

Animals↗
PubMed1995

Patterns of rod proliferation in deep-sea fish retinae.

In a sample of 37 species of deep-sea fish species from the sea floor of the Porcupine Seabight and the Gobal spur (North Atlantic) we investigated the overall structure of the retina with special respect for the organization of rods, their length and their arrangement in multiple banks. Using an immunocytochemical marker for cell proliferation (PCNA) we studied the mechanisms of rod proliferation, and, by means of serial section reconstruction followed their integration into the existing population of rods. Furthermore, in three different species we have observed growth related changes in retinal thickness, rod density and proliferation activity. We found evidence for two different principles for the organization of rods in these deep-sea fish retinae. In the first group of species represented by Nematonurus armatus and Coryphaenoides guentheri we found rods to be rather short (20-30 microns) and arranged in three and more banks. In these species rod proliferation occurred in a single band of cells immediately vitread of the external limiting membrane, thus showing a high degree of spatial and temporal order. In these species, young rods are inserted just sclerad of the external limiting membrane and the older outer segments pushed away from the incoming light towards the back of the eye. This may be linked to a progressive loss of function of the older rods and might represent an alternative mechanism to the disk shedding in other vertebrates. In the second population (e.g. Conocara macroptera, Alepocephalus agassizii) we observed considerably longer rod outer segments (60-80 microns) forming no more than two layers. These retinae had rod precursors arranged in disseminated clusters throughout the outer nuclear layer indicating the lack of clear spatio-temporal order in mitotic activity along with a more statistical pattern of integration of the newly formed outer segments. In our sample of species both populations were of about equal size suggesting that the two mechanisms are equally effective and may have arisen independently.

Animals↗
PubMed1995

Localization of dopamine D1-receptors in vertebrate retinae.

We used the fluorescent labelled dopamine D1-receptor antagonist Bodipy-SCH 23390 for the cellular localization of D1-ligand binding sites in the retinae of different vertebrates (teleosts, Xenopus, turtle, rat and rabbit). Competition experiments with unfixed cryosections of fish retina were performed to characterize the binding conditions of Bodipy-labelled SCH 23390. Tissue bound [3H]SCH 23390 was displaceable with increased amounts of bodipy-SCH 23390. The pharmacological specificity of the D1 fluorescent antagonist was determined by competition experiments with an excess of unlabelled SCH 23390. This treatment significantly reduced the level of fluorescence of the retina confirming the specificity of the binding. We observed a homogeneously distributed fluorescence signal in both plexiform layers in unfixed cryosections of fish, frog, turtle, rat and rabbit. Similar staining intensities of both plexiform layers were found in frog, turtle, rat and rabbit retina. In teleosts, the label of the outer plexiform layer was markedly more intense. Non-specific label was associated with photoreceptor outer and inner segments. The specific labelling of both plexiform layers indicates a mismatch of dopamine releasing and D1-binding sites, and suggests a possible extrasynaptic localization of the D1-receptor. The physiological significance of the observed distribution of D1-ligand binding sites is discussed with respect to the role of dopamine in controlling adaptational processes in the retina.

Animals↗
PubMed1995

Determination of the number of Epstein-Barr virus genomes in whole blood and red cell concentrates.

The risk of Epstein-Barr virus (EBV) infection after blood transfusion has been controversially discussed. Little is known about EBV transmission via buffy-coat-depleted red cell concentrates (RCC). In this study, we determined the number of EBV genomes in RCC of EBV-seropositive donors in comparison to whole blood. RCC were prepared from whole blood donations by using the 'top and bottom system'. Leucocyte content was significantly reduced in RCC in comparison to whole blood (0.47 x 10(9) vs. 2.3 x 10(9) per unit; P < 0.001). As B cells are expected to harbour EBV genomes, we analysed the number of B lymphocytes in both types of blood products. There was a significant reduction of B cell content from a median value of 90 x 10(6) in whole blood to 0.2 x 10(6) in RCCs (P < 0.001). The number of EBV genomes was estimated at a median value of seven from 10(6) B cells in the peripheral blood of healthy, EBV-seropositive blood donors by means of a polymerase chain reaction (PCR) assay. By calculation, one unit of RCC may contain an average of one to two EBV genomes, in contrast to a whole blood unit, which is likely to harbour an average of 600 to 700 EBV genomes. It is concluded that the use of leucocyte depletion systems significantly reduces the number of EBV genomes in erythrocyte concentrates. Thus, leucocyte reduced blood products appear to minimize the risk of EBV infection.

B-Lymphocytes↗
PubMed1995

Increase of antigen production in BLV-infected cell lines via additional expression of tax.

The selection of animals infected with the bovine leukaemia virus (BLV) is performed by the immunological detection of antibodies against the virus, commonly using the antigen gp51. Furthermore, research is being carried out to develop protective vaccines against BLV that have gp51 as their main component. Taking both of these factors into account, it is clear that there will be an increasing requirement for the virus antigen gp51 for some time to come. The permanently BLV-infected foetal lamb kidney cell line FLK/BLV (and its sublines) has been proved to be the most useful culture for the mass production of the virus antigen. Stable cell lines producing higher quantities of BLV antigen have not been established, either by subcloning of the FLK/BLV or by infection of other permanent cells with BLV. Here, a report is made on efforts to increase the expression of gp51 in BLV-infected cells via the additional expression of homologous transactivating virus protein tax. Selectable tax expression vectors that integrate into the host cell genome were constructed using BL provirus DNA fragments. Highly productive FLK/BLV cells were transfected with these vectors. Following selection with G 418, gp51-producing cell lines were established and tested for their productivity for several months. Some tax-vector-containing cell lines have produced 1.5-2 times more gp51 than the highly productive parental control cell line FLK/BLV 44-1.

Animals↗
PubMed1995

Cytokine production in a whole-blood assay after Epstein-Barr virus infection in vivo.

Epstein-Barr virus (EBV) has a marked tropism for cells of the immune system, and infection can result in profound immunomodulatory effects. In order to examine the role of cytokines during the acute phase of infectious mononucleosis, we studied the levels of different interleukins (ILs), interferons (IFNs), and the soluble IL-2 receptor (sIL-2R) in serum samples of 20 patients. We found elevated levels of IL-2, IL-6, sIL-2R, and IFN-gamma. Whereas the peak of IL-2 and IL-6 concentration occurred during the first week (P < 0.01), the largest amounts of sIL-2R were measured during the second week (P < 0.01). IFN-gamma levels were only enhanced during the first week. In addition, we investigated the ability to produce cytokines in response to mitogenic stimulation in a whole-blood assay of 11 patients compared with healthy blood donors. In the whole-blood assay of patients compared with controls after stimulation with lipopolysaccharide, we measured more than 10-fold elevated levels of tumor necrosis factor alpha (P < 0.01), 3-fold elevated levels of IL-1 beta (P < 0.01), and about 2-fold increased amounts of IL-6 (P < 0.01). A significant enhancement in sIL-2R and IFN-gamma concentration was found in the assay after stimulation with phytohemagglutinin after 24 h of incubation (P < 0.01). Collectively, our data seem to indicate that monocytes are strongly activated during infectious mononucleosis. Monocytes and monocyte-derived factors may play an important role in the pathogenesis of infectious mononucleosis and, together with T lymphocytes, may be partly responsible for clinical symptoms.

Adult↗
PubMed1995

Characteristics of viral protein expression by Epstein-Barr virus-infected B cells in peripheral blood of patients with infectious mononucleosis.

The frequency of Epstein-Barr virus (EBV) antigen-positive B cells in the peripheral blood of patients with infectious mononucleosis compared with that for latently EBV-infected individuals was examined by immunocytochemistry. B cells positive for Epstein-Barr nuclear antigen (EBNA) 1, EBNA2, and latent membrane protein were frequently found in all peripheral B lymphocyte preparations from 25 patients suffering for 3 to 28 days from infectious mononucleosis by using monoclonal antibodies and the alkaline phosphatase anti-alkaline technique. There was a significant decrease in the number of positive B cells during the course of disease. EBNA1-positive B cells were detected in 0.01 to 2.5% of total B cells (median, 0.8%), EBNA2-positive B cells were detected in 0.01 to 4.5% of total B cells (median, 0.9%), and latent membrane protein-positive B cells were detected in 0.01 to 1.8% of total B cells (median, 0.5%), depending on the duration of clinical signs. In contrast, we did not find any EBNA1- or EBNA2-positive B cells in 2 x 10(6) peripheral blood B lymphocytes of 10 latently EBV-infected individuals, whereas aliquots of the same cell preparations were EBV DNA positive by a PCR assay. Therefore, it appears to be possible to detect infectious mononucleosis by immunocytochemical determination of latent EBV products, which might be of relevance for the diagnosis of EBV reactivations in immunosuppressed patients.

Adolescent↗