Nitric oxide synthase in Müller cells and neurons of salamander and fish retina.

Nitric oxide synthase (NOS) is the biosynthetic enzyme of the signaling molecule nitric oxide (NO). NO donors have been reported to modulate conductances in cell types throughout the retina, from photoreceptors to ganglion cells. Previously, NOS immunoreactivity has been reported in amacrine cells and cells within the ganglion cell layer. Here, we have examined the cellular localization of NOS in the retinas of salamander, goldfish, and catfish using both an affinity-purified antiserum to brain NOS and NADPH diaphorase (NADPHd) histochemistry. These markers indicate that an NOS-like enzyme is localized not only to presumptive amacrine cells but also, depending on the species, to photoreceptor ellipsoids, to somata within the ganglion cell layer, and to horizontal cells. In addition to these neurons, our results indicate that Müller cells, the radial glia of the retina, also contain an NOS-like enzyme. In support of this latter conclusion, cells morphologically similar to Müller cells were positive for NADPHd staining in all three species. In salamander, NOS-like immunoreactivity, NADPHd staining, and binding of anti-GFAP (a marker for glia) were localized to cells that were morphologically indistinguishable from Müller cells. In goldfish, reactivity to both anti-NOS and anti-vimentin (a marker for glia) colocalized to radial processes extending through the inner retina to the inner limiting membrane. These observations are the first to indicate the presence of an NOS-like enzyme in Müller cells and suggest that these glia could be a ready source of NO for target neurons throughout the retina.

Cyclic nucleotide regulation of teleost rod photoreceptor inner segment length.

Retinal rod photoreceptors of teleost fish elongate in the light and shorten in the dark. Rod cell elongation and shortening are both mediated by actin-dependent mechanisms that occur in the inner segment myoid and ellipsoid. The intracellular signaling pathways by which light and dark regulate the actin cytoskeleton in the inner segment are unknown. To investigate the intracellular signals that regulate teleost rod motility, we have been using mechanically isolated rod inner/outer segments (RIS-ROS) obtained from the retinas of green sunfish, Lepomis cyanellus. In culture, RIS-ROS retain the ability to elongate in response to light; myoids elongate 15-20 microns in length during 45 min of light culture. A pharmacological approach was taken to investigate the role of cyclic nucleotides, cyclic nucleotide-dependent kinases, and protein phosphatases in the regulation of RIS-ROS motility. Millimolar concentrations of cAMP and cGMP analogues were both found to inhibit light-induced myoid elongation and two cyclic nucleotide analogues, SpCAMPS and 8BrcGMP, promoted myoid shortening after RIS-ROS had elongated in response to light. The cyclic nucleotide-dependent kinase inhibitor, H8, mimicked light by promoting myoid elongation in the dark. The effects of H8 were dose dependent, with maximal elongation occurring at concentrations of approximately 100 microM. Similar to the effects of cyclic nucleotide analogues, the phosphatase inhibitor, okadaic acid (0.1-10 microM), inhibited light-induced elongation and promoted shortening. The results presented here suggest that RIS-ROS motility is regulated by protein phosphorylation: phosphorylation in the dark by cyclic nucleotide-dependent protein kinases promotes rod shortening, while dephosphorylation in the light promotes rod elongation.

Light-activation of teleost rod photoreceptor elongation.

Rod photoreceptors in the retinas of teleost fish undergo changes in cell length in response to changing ambient light intensities. In the dark rods shorten and in the light rods elongate. These movements are mediated by actin-dependent processes which occur in the ellipsoid and myoid of the inner segment. As an approach to examining the underlying intracellular signaling pathways that link light absorption to actin-dependent motility in the inner segment, we have investigated the quantitative aspects of the light stimulus required to activate elongation in isolated rod inner/outer segments (RIS-ROS) of the green sunfish (Lepomis cyanellus). The intensity thresholds and strength-duration characteristics of the light stimulus required to activate teleost rod elongation were found to differ from those reported to activate vertebrate rod membrane hyperpolarization. In response to brief pulses of light, RIS-ROS elongated in a graded manner, both as a function of increasing light pulse intensity and light pulse duration. Half maximal activation of light-induced RIS-ROS elongation was produced by a stimulus of roughly 6 x 10(15) photons cm-2, which is calculated to bleach approximately 20% of the photopigment molecules in green sunfish rod outer segments. This degree of photopigment bleach is approximately 6-7 orders of magnitude greater than that required to elicit half maximal changes in membrane potential in other vertebrate rod preparations. Furthermore, the reciprocal relationship between light pulse intensity and duration in eliciting an equal elongation response held for relatively long light pulse durations.(ABSTRACT TRUNCATED AT 250 WORDS)

[Profundaplasty--a palliative operation in leg arterial occlusion of the aged?]. / Die Profundaplastik--eine Palliativoperation beim Beinarterienverschluss des alten Menschen?

In a retrospective study the relevance of revascularisation of the deep femoral artery was evaluated in 100 geriatric patients with obliterative atherosclerosis. The results of profundaplasty were good in 91% of patients with claudication (follow-up 47 months). In patients with rest pain the limb salvage rate was 77% (follow-up 39 months). In comparison with femoropopliteal or femorocrural bypass the results were at least even but had lower lethality. In a state of gangrene the limb salvage rate was 39% overall (follow-up 31 months). Diabetics had a limb salvage rate of 28% versus 43% in non diabetics. In a state of claudication and rest pain with stenosis of the deep femoral artery its revascularisation is in our view the treatment of first choice. In a state of gangrene bypass implantation, especially in diabetics, seems to have better results, but as additional palliation before primary amputation profundaplasty should be performed.

[Intra-arterial digital subtraction angiography of the femoral bifurcation as a supplement to conventional pelvic-leg arteriography]. / Intraarterielle DSA der Femoralisgabel als Ergänzung zur konventionellen Becken-Bein-Arteriographie.

In view of the fact that in prognosis and treatment of arterial occlusion, particular importance must be attached to the profunda femoris artery, and especially to the region of origin of this artery, it is imperative to achieve angiographic representation of the descent of the profunda femoris artery without any masking. The intra-arterial injection method employing digital subtraction angiography is the method of choice, since it requires a low amount of contrast agent, time, and film. In 90 per cent of the cases, ipsilateral anterior oblique projection will be most suitable to represent the femoral bifurcation, which depends on the course of the profunda femoris artery in anterior-posterior projection, the angle varying between 30 degrees 40 degrees. 50 to 70 per cent of the stenoses occurring in the descending part of the profunda femoris artery, can be recognised via oblique projection only.

Acute elevation of cyclic AMP does not alter the ion-conducting properties of the neuronal nicotinic acetylcholine receptor of PC12 cells.

The nicotinic acetylcholine receptor of Torpedo californica has been shown to be subject to cyclic AMP-dependent phosphorylation, raising the possibility that nicotinic receptors may be regulatable by phosphorylation. To investigate this possibility for a neuronal nicotinic receptor, we have studied the effects of elevation of cyclic AMP on the ion-conducting properties of the nicotinic receptor of PC12 cells. The cyclic AMP content of the cells was altered by exposure to various concentrations of forskolin (an activator of adenylate cyclase) for periods of time ranging from 1 to 40 min. Receptor activation then was measured as agonist-induced influx of 86Rb+ into the cells. Throughout a variety of conditions, no changes in agonist-induced ion influx were detected. This was true regardless of the concentration of agonist used, the duration of receptor stimulation that was measured, the concentration of forskolin employed, or the duration of elevation of cyclic AMP prior to receptor activation. Experiments designed to measure receptor desensitization also were unable to detect any differences upon elevation of cyclic AMP. Finally, the antagonism of receptor activation by substance P also was not affected by elevation of cyclic AMP. Thus, no evidence could be obtained in these cells supporting the hypothesis that a neuronal nicotinic acetylcholine receptor can be acutely regulated by changes in cellular cyclic AMP.

[Recent aspects in the diagnosis and therapy of inflammatory aneurysms of the abdominal aorta]. / Neurere Aspekte zur Diagnostik und Therapie des inflammatorischen Bauchaortenaneurysmas.

The so-called inflammatory infrarenal abdominal aneurysm is characterized by huge perianeurysmal retroperitoneal fibrosis, which may achieve a size of more than 1 to 2 cm. It impeats the surgical proceeding enormously. By means of computed tomography a diagnosis of this kind of aneurysm can already be given before the operation. A therapy of the fibrosis resp. the hereby caused complications especially in the urinary system is not an essential in the first place due to the fact that these complications tend to vanish spontaneously after the resection of the aneurysm.