Different types of synapses with different spectral types of cones underlie color opponency in a bipolar cell of the turtle retina.

Electrophysiologically, color-opponent retinal bipolar cells respond with opposite polarities to stimulation with different wavelengths of light. The origin of these different polarities in the same bipolar cell has always been a mystery. Here we show that an intracellularly recorded and HRP-injected, red-ON, blue/green-OFF bipolar cell of the turtle retina made invaginating (ribbon associated) synapses exclusively with L-cones. Non-invaginating synapses resembling wide-cleft basal junctions were made exclusively with M-cones. Input from S-cones was not seen. From these results we suggest sign-inverting transmission from L-cones at invaginating synapses via metabotropic glutamate receptors, and sign-conserving transmission from M-cones at wide-cleft basal junctions via ionotropic receptors. To explain the pronounced blue sensitivity of the bipolar cell, computer simulations were performed using a sign-conserving input from a yellow/blue chromaticity-type (H3) horizontal cell. The response properties of the red-ON, blue/green-OFF bipolar cell could be quantitatively reproduced by this means. The simulation also explained the asymmetry in L- and M-cone inputs to the bipolar cell as found in the ultrastructural analysis and assigned a putative role to H3 horizontal cells in color processing in the turtle retina.

Effects of horizontal cell network architecture on signal spread in the turtle outer retina. Experiments and simulations.

In the Pseudemys turtle retina five functionally distinct, electrically coupled networks of horizontal cells distribute signals in the outer plexiform layer. These networks differ significantly in their architecture, as determined by intracellular labeling with Neurobiotin after physiological recording and identification. The density of H1 horizontal cells is highest, ranging around 1800 cells/mm2 at approximately 2.3 mm eccentricity. H1 horizontal cell somata are connected via 6-10 thin, short dendrites. The H1 horizontal cell axon terminal network is composed of thick axon terminals, forming a three-dimensional, sheath-like structure. Networks of coupled H2 and H3 horizontal cells have cell densities of around 210 cells/mm2 and 350 cells/mm2, respectively, at the same eccentricity of 2.3 mm. Cell bodies are connected with 6-12 long, thin dendrites. Here we report for the first time H4 horizontal cell networks. Cell density is approximately 970 cells/mm2 at 2 mm eccentricity, and cell bodies are connected with 6-10 thin, short dendrites. General properties of passive voltage spread were compared for three of these horizontal cell networks using NeuronC. Realistic network architectures were obtained by digitizing the intracellularly labeled networks, respectively. One network obtained from coupled H1 horizontal cell bodies, one from coupled H1 horizontal cell axon terminals, and one from H2 horizontal cells were simulated. These three realistic networks were compared with an artificial, electrically coupled regular triangular network. Passive signal spread in these networks strongly depended on the exact network architecture using otherwise identical parameters. Changes in coupling strength affected signal spread in these networks differently. As in the experimental situation, changes in synaptic conductance influenced signal spread. Some principal effects of extensively coupled horizontal cells on photoreceptor signal processing were simulated with one type of photoreceptor connected by telodendria, synapsing onto an underlying triangular network and receiving feedback synapses. Under certain conditions, spatial information is coded in single photoreceptors. This was also the case in the experimental situation. In the simulation, spatial filter adjustment for optimal spatial coding in photoreceptors can be achieved by changing coupling strength in the horizontal cell network.

A geometrical description of horizontal cell networks in the turtle retina.

Networks of physiologically identified H2 horizontal cells in the turtle retina were labeled by intracellular injection of Neurobiotin. We obtained a quantitative description of the neighbourhood relations in the dye-coupled cell mosaics by using the somata as centers for the Voronoi-Delaunay construction. Computational models simulating the experimental data are presented.

[Primary non-Hodgkin's lymphoma of the stomach]. / Primäre Non-Hodgkin-Lymphome des Magens.

Between 1980 and 1987 a total of 17 patients were operated upon in curative intention of the Non-Hodgkin-Lymphoma of the stomach at our surgical department. Ten of these patients were within Ann-Arbor-Stage I, four within stage II/1 and the other three within stage II/2. In six cases we found low-malignant and in the other 11 cases high-malignant tumors. One patient died postoperatively after a myocardial infarction, one female died four months postoperatively in spite of chemotherapy of the disease. 15 patients (94%) are still alive today without any new symptoms of the disease, within a median average observation time of 40.6 months.

[Changes in the transmural electric potential difference in the region of stomach ulcer. Local effect of sucralfate, aluminum hydroxide and magnesium trisilicate]. / Veränderungen der transmuralen elektrischen Potentialdifferenz im Bereich des Ulcus ventriculi. Eine Studie zur lokalen Wirkung von Sucralfat, Aluminium-Hydroxid und Magnesium-Trisilikat.

In three groups of six patients with gastric ulcer, sucralfate, aluminium hydroxide and magnesium trisilicate, respectively was applied to the ulcer under endoscopic vision. Prior to, two and four hours after application of these substances, the transmural electrical potential difference (p.d.) was measured in the region of the bed of the ulcer, the margin of the ulcer, the antrum on the lesser curvature side, and in the pool of juice; additionally, the degree of adherence of the substances to the floor of the ulcer was recorded. After sucralfate, the increase in p.d. in the bed of the ulcer was clearly greater two and four hours post-application than after the two antacids tested, and adherence to the ulcer was also more marked and longer lasting. These findings confirm the superior local protective effect of sucralfate in the bed of the ulcer on the basis of its physico-chemical properties, as compared with the antacids tested. These clinico-experimental findings correlate with the efficacy of sucralfate in ulcer disease as demonstrated in clinical studies.

[Hyperplasiogenic gastric polyps and stomach cancer. Endoscopic findings of early stomach cancer in 3 out of 42 biopsies of hyperplasiogenic polyps]. / Hyperplasiogene Magenpolypen und Magenkarzinome. Endoskopische Beobachtung von Magenfrühkarzinomen bei drei von 42 biopsierten hyperplasiogenen Polypen.

The hyperplasiogenic gastric polyp is an organo-specific polyp and compared to the real adenoma of the stomach and colon is not a neoplasia. The formation of a carcinoma in or on a hyperplasiogenic polyp is extremely rare. Hyperplasiogenic polyps have more of an indicator function, indicating an ill mucous tissue and the possibility of the formation of a carcinoma and a precancerous condition. Three observations of the formation of early carcinoma of the stomach in or on hyperplasiogenic polyps in 42 patients with hyperplasiogenic polyps, which were found in the upper alimentary tract in the course of 4 years and 10.473 endoscopic investigations, are reported here. Due to these observations the endoscopic loop extraction of all polypous protuberances still seems to be necessary.

[Ranitidine and cimetidine in the prevention of stress: ulcer hemorrhage a prospective comparative multicenter study]. / Ranitidin und Cimetidin in der Prophylaxe der Stressulcus-Blutung: Eine prospektive Multicenter-Vergleichsstudie.

In a multicentre single-blind study, ranitidine was compared to cimetidine as prophylactic treatment against stress-induced upper gastrointestinal bleeding in seriously ill patients in the intensive care unit (ICU). 380 patients entered the study. 192 patients were treated with ranitidine 50 mg q.i.d. as i.v. bolus followed by 150 mg orally twice daily. 188 patients received cimetidine 400 mg q.i.d. intravenously and 1,000 mg daily orally in divided doses. Five patients in the ranitidine group (2.6%) and 12 in the cimetidine group (6.4%) developed gastrointestinal bleeding definitely or possibly due to stress lesions. This difference was not significant. The incidence of stress erosions or ulcerations developing during the study was 11.8% for the ranitidine group and 18.3% for the cimetidine group (non-significant difference). Adverse events in the ranitidine group were nausea, tachycardia or vomiting in 4 patients. 5 cimetidine-treated patients developed cholestasis, and 5 additional central nervous system problems. The high degree of efficacy of both drugs compared very favourably with the high incidence of stress ulceration and hemorrhage in similar untreated populations.

Cimetidine for anastomotic ulcers after partial gastrectomy. A randomized controlled trial.

In a randomized double-blind multicenter trial, 15 outpatients with endoscopically proved anastomotic ulceration after Billroth I or Billroth II partial gastrectomy received cimetidine, 1 g daily over eight weeks, or a placebo. All patients also received antiacid. The ulcer healed completely in all seven cimetidine-treated patients and in one of the eight placebo-treated patients (P less than 0.01). Ulcers not healed during the double-blind phase of the trial were all subsequently healed on open cimetidine treatment. There was a trend toward improvement of daytime symptoms in favor of cimetidine (P = 0.06), and nighttime symptoms were significantly relieved during the initial four weeks of cimetidine treatment P = 0.02). We conclude that cimetidine, 1 g daily, promotes healing of anastomotic ulcers after partial gastrectomy.

[Endoscopic measurement of transmucosal potential differences of the stomach (author's transl)]. / Uber die Messung der transmuralen elektrischen Potentialdifferenz des menschlichen Magens unter endoskopischer Sicht.

Recording of the transmural electric potential differences (PD) of the stomach by endoscopic control demonstrate significant differences between antral and corpus mucosa. In ulcers there is a drop of PD in the circumference, PD is nearly zero in the ground of the ulcers. These results possibly are references to the origin of ulcers.