[What should urologists know about SARS-CoV-2? Risk analysis for urological operations and recommendations for action in clinical routine]. / Was sollte ein Urologe zu SARS-Cov-2 wissen? Risikoanalyse für urologische Operationen und Handlungsempfehlungen im klinischen Alltag.

BACKGROUND: COVID-19 poses a challenge to healthcare systems worldwide. Due to the increasing number of cases, surgeons in urology have also been confronted with SARS-CoV­2 infections. Thus, there is an urgent need for clinical guidance and recommendations. AIM: Our work aims to create a widespread assessment of a possible risk for infection with SARS-CoV­2 during surgical procedures. Based on current data and current national and international guidelines, we try to assess the risk of infection when handling human tissue and the necessary hygienic measures that are needed. Finally, recommendations for daily urologic work are derived and explained. MATERIALS AND METHODS: The current literature in PubMed, bioRxiv and medRxiv and data available from the WHO and Robert-Koch-Institut on SARS-CoV­2 and surgical procedures in (potentially) infected patients are reviewed. The endpoint of our research was 21 April 2020. CONCLUSION: Based on our research, general and specific recommendations for clinical urologic praxis can be derived. Although it remains unclear whether SARS-CoV­2 is transmitted via the aerosols produced, current PPE in operating rooms probably does not offer sufficient protection during surgical interventions during the SARS-CoV­2 pandemic. Use of FFP­2 masks, safety goggles and full-body protective suits is crucial. To contain viral spread on surfaces and personnel, complex filter systems (HEPA) should be used as well as closed suction devices during surgery. Combined with consequent disinfection of surfaces and behavioral measures, a safe environment for healthcare workers in urology can be created. Thus, according to current knowledge, we believe that emergency and urgent surgical procedures are not contraindicated, provided that appropriate precautionary safety measures are followed.

The fate of ultraviolet receptors in the retina of the Atlantic salmon (Salmo salar).

We have shown that fully differentiated cones in the salmon retina die as a result of apoptosis (normal cell death). These putative UV cones begin to disappear from the main retina when the fish is aged 120 days and are completely absent at day 220. However, they continue to be produced in the growth zones, ora serrata and ventral fissure, where they are shortlived and never incorporated into the main retina. The dying cones in the main retina and the growth zones are engulfed by macrophages and Müller cells.

Ontogenesis of diurnal rhythms of cAMP concentration, outer segment disc shedding and retinomotor movements in the eye of the brown trout, Salmo trutta.

Histological analyses of the retina of Salmo trutta post-embryos exhibit rhythmic disc shedding at 6 weeks, followed by cyclic retinomotor movements at 7 weeks. Diurnal variations in cAMP concentration, as established by a radioreceptor assay, develop simultaneously with retinomotor movements and are fully expressed at 9.5 weeks. In continuous darkness, neither retinomotor movements nor intra-ocular peaks of cAMP occur, indicating that the endogenous oscillator for retinomotor movements and cAMP levels is not yet developed.

Retinal morphogenesis in the rainbow trout, Salmo gairdneri.

The post-embryonic development of the neural retina and the pigment epithelium of the rainbow trout was analysed by electron microscopy. Particular attention was paid to the period when these fish change from photonegative to photopositive behaviour. In photoreceptors, light-sensitive outer segments arise prior to synapses. Subsequent rapid synaptogenesis in the inner plexiform layer results in the establishment of the pathway between photoreceptors and ganglion cells. Interreceptor contacts and feedback synapses, associated with the integration of colour and spatial information, appear when the fish become photopositive, swim to the water surface and begin exogenous feeding. Retinal development parallels that of higher optic centres and visual acuity, as reported by other authors.

Tracts of putative ultraviolet receptors in the retina of the two-year-old brown trout (Salmo trutta) and the Atlantic salmon (Salmo salar).

We previously showed that the brown trout possesses UV-sensitive cones in its retina that are lost in 2-year-old fish. However, present investigations reveal that in the narrow growth zone along the periphery and the ventral embryonic fissure, the formation of these cones continues in trout and salmon.

Ultraviolet receptors, tetrachromatic colour vision and retinal mosaics in the brown trout (Salmo trutta): age-dependent changes.

Microspectrophotometric analysis of the visual receptors of "yearling" brown trout, Salmo trutta, revealed three cone types, double cones with visual pigments absorbing maximally at about 600 and 535 nm, and two types of single cone with lambda max at about 440 and 355 nm. Two-year-old fish did not possess the u.v. cone cells. Microscopical analysis of the cone mosaic in "yearling" trout showed a square pattern of double cones with a central single cone and corner single cones, but in two-year-old trout the corner cones were absent. It is concluded that u.v. sensitivity is derived from the corner cones of the mosaic, and that it is only present in young trout.

Differentiated retinal Müller glia are ciliated--ultrastructural evidence in the teleost Poecilia reticulata P.

It is generally held that the cells in all retinal layers bear a cilium during development but there have been controversial reports as to whether the ciliation of the Müller cell persists after birth. The present study of the developing and fully formed adult eye of the teleost Poecilia reticulata reveals that just prior to the formation of the photoreceptors in the embryonic retina, the Müller cell contains only a diplosome. Throughout development the diplosome is seen to migrate apically, always juxtaposed to many microtubules. When the photoreceptors are differentiated and capable of photomechanical movement, the Müller cell in Poecilia bears a cilium situated vitreally to the external limiting membrane. The cilium persists in juvenile and adult retinae in both the light- and dark-adapted state. The functional significance of the cilium in the Müller cell is presently unknown.

The visual pigments of the weever fish, Trachinus vipera: a microspectrophotometric study.

Microspectrophotometric analyses of the visual pigments of the weever fish, Trachinus vipera, demonstrate the presence of a rhodopsin with peak sensitivity at 502 nm, and two cone visual pigments. Identical twin cones are green-sensitive containing a P5281, and single cones are blue-sensitive containing a P4401. The dichromacy of the weever is discussed in relation to its photic environment and feeding behaviour.

The eye of the venomous marine teleost Trachinus vipera with special reference to the structure and ultrastructure of visual cells and pigment epithelium.

The benthic Trachinus vipera occurs to a depth of 50 m and migrates inshore during the summer. It lies buried in the sand with the top of its head exposed. The benthic habitat and predatory behaviour, tuned to function in twilight, are reflected in the structure and ultrastructure of the eye. The eye is well camouflaged by an iridescent cornea and a differentially coloured spectacle. The spontaneous eye movements are either coordinated, for binocularity, or independent, for monocular vision. The latter is aided by the reduction of the blind spot to a thin streak. Consequently the optic nerve is flattened. When leaving the eyeball it becomes folded, which may allow for lengthening. The cones of the duplex retina are arranged in a square mosaic, with a central single cone and identical twin cones. The square mosaic is stabilized by an intricate framework of so-called "fins", and the twin cones do not "twist" into a row pattern in the dark as observed in the diurnal guppy. The twin cones do not extend sclerally in the dark, while the single cones, rods and pigment epithelial processes undergo retinomotor movements. Regional differences are observed: The sensitivity of the dorsal retina is enhanced by a great number of rods, bundled as in deep-sea fish. The lipid granules in the dorsal pigment epithelium may act as a tapetum lucidum, reflecting light back through the retina. A cluster of triple cones in the dorso-temporal region may represent a site for increased sensitivity and/or acute vision. An unusual inclusion body, with a dense core similar to a lipid droplet, and surrounded by membranes, is observed in the dorsal pigment epithelium. The membranes are seen to be continuous with the smooth endoplasmic reticulum, nuclear membrane and myeloid bodies. This body changes diurnally and may be a type of phagosome.

Myeloid bodies in the pigment epithelium of a teleost embryo, the viviparous Poecilia reticulata.

Appearance of myeloid bodies (MB) in the retinal pigment epithelium (RPE) precedes photoreceptor outer segment development in Poecilia reticulata embryos reared under a 12 hrs LD cycle, in constant darkness (DD) and constant light (LL). When first formed, MB are predominantly continuous with rough endoplasmic reticulum (RER). The same is observed in the peripheral growth zone of the developed eye, whereas in differentiated parts, MB are continuous with the smooth endoplasmic reticulum (SER). At onset of photomechanical movements, wavy MB predominate in light-adapted LD embryos, are exclusively present in LL and are located in the RPE processes. SER abounds. Straight MB predominate in dark-adapted LD embryos, are exclusively present in DD and contain electrondense material between lamellae. Diurnal appearance of electrondense material may be coupled with transfer of retinol, mediated by various transport proteins.

Ultrastructural diurnal changes of the retinal photoreceptors in the embryo of a viviparous teleost (Poecilia reticulata P.).

All diurnal changes studied - ellipsosome excepted - start at midgestation, following differentiation of photoreceptors and pigment-epithelium cells. These are: (1) shedding of the tips of the light-sensitive photoreceptor outer segments and subsequent phagocytosis by the pigment-epithelium; (2) retinomotor movements of pigment-epithelium processes, rods and cones; (3) changes of cone square-mosaics into row-mosaics at night. Newly-differentiated photoreceptors in the embryo are, therefore, already vulnerable to disruption of cyclical systems. Several inherited human retinal diseases, such as Retinitis pigmentosa, are thought not to affect differentiation of photoreceptors but their cyclical renewal pathways. The retina of the guppy-embryo is, therefore, a valuable model for such studies.

Prevention of continuous light-induced anovulation in rats by early exposure to continuous light.

Continuous illumination (LL) beginning at 22 days of age caused precocious puberty followed by persistent estrus with anovulation in female offspring originating from mother rats exposed to a 14L:10D light-dark cycle prior to and during pregnancy. However, LL had no deleterious effect on reproductive cycles of offspring reared in LL and originating from mothers exposed to LL prior to and during pregnancy. These rats had a normal onset of puberty in LL, a normal 4-day estrous cycle, a periodic rise of plasma estrogen prior to the periodic appearance of the preovulatory luteinizing hormone (LH) surge, and spontaneous ovulation in LL continued until at least 300 days of age. Also, the female offspring of these rats showed a similar resistance to the deleterious effects of LL on cyclic ovulation. These results support the following interpretation: 1) offspring from mother rats exposed to LL prior to and during pregnancy become insensitive to the deleterious effects of LL on cyclic ovulation, 2) neural elements controlling cyclic release of LH are not totally photoperiod (14L:10D)-dependent, and 3) in the absence of daily 14L:10D signals, an endogenous clock, possibly timed by daily laboratory signals (temperature, noise, taking of vaginal smears), may provide time cues for cyclic LH release.

Ontogeny of the photoreceptors in the embryonic retina of the viviparous guppy, Poecilia reticulata P. (Teleostei). An electron-microscopical study.

Ultrastructural analyses of retinal development in the guppy embryo show that at midgestation all types of photoreceptors are differentiated in the fundus, and at birth differentiation extends over the whole retina. Formation of discs of outer segments is more rapid in rods than in cones. Double cones differentiate simultaneously with long single cones and are formed by the adhesion of two primordial inner segments; short single cones develop last. Wherever cones are differentiated, they are arranged in an adult-type square mosaic. The rods in the embryo, as opposed to the adult, are likewise regularly arranged within the mosaic unit. These results are at variance with the generally held opinion that adult teleosts which possess duplex retinae have larvae with pure cone retinae, and that rods, double cones and mosaics appear in late larval life or only at metamorphosis. In the double cones of the guppy embryo subsurface cisternae develop along the adjoining primordial inner segments. Additionally, regularly distributed subsurface cisternae are formed in the regions of intimate contact of long single cones with double cones and rods. We suggest that the early development of rods and double cones, and a square-mosaic with regular distribution of rods and subsurface cisternae, provide the newly born with a fully functional optical apparatus, especially suited to perception of movements. This is necessary for its survival against predatory, especially maternal, attacks.

Cone mosaics in a teleost retina: changes during light and dark adaptation.

The square mosaic pattern of retinal cones in the guppy, Poecilia reticulata, changes during dark adaptation into a row mosaic. The functional significance of this change is discussed.

Effect of D-Trp6-LH-RH on the pituitary-gonadal axis during the luteal phase in the baboon.

An effect of E-Trp6-LH-RH (superactive LH-RH agonist) in the pituitary and ovarian function was examined. Four regularly cycling baboons were used for this study. After determination of control values of plasma levels of LH, oestrogen and progesterone during the entire menstural cycle, D-Trp6-LH-RH was infused subcutaneously for 7 days during the early luteal phase in these four baboons. An infusion of D-Trp6-LH-RH increased plasma LH and oestrogen, but it failed to alter the plasma level of progesterone. From these results, it seems unlikely that 1) D-Trp6-LH-RH has a luteolytic effect, and 2) an increased ovarian oestrogen causes luteolysis in the baboon.

Ellipsosomes: organelles containing a cytochrome-like pigment in the retinal cones of certain fishes.

Ellipsosomes are dense spherical bodies containing a very large concentration of a heme pigment spectroscopically resembling pure cytochrome c. They are located at the outer ends of the inner segments of the cones of certain fishes. Although, superficially, they resemble the similarly located oil droplets in the cones of birds and reptiles, their ultrastructure and staining properties resemble those of the neighboring mitochondria. However, like the oil droplets, they may serve as intracellular color filters.

'Disk shedding' in the cone outer segments of the teleost, Poecilia reticulata P.

Electron microscopical observations show that the cones in the retina of the diurnal Poecilia reticulata shed their membranous outer segment disks. This occurs at the side of the disk which is open to the extracellular space. Shedding is observed in single and twin cones and occurs at any level of the outer segment. The disks are not discarded in packages or as single disks, but are shed in small vesicular portions. This mode of 'disk shedding' may explain why in cone outer segments radioactively labelled replacement protein is diffusely distributed.

The accessory outer segment of rods and cones in the retina of the guppy, Poecilia reticulata P. (Teleostei). An electron microscopical study.

The ultrastructure of the accessory outer segment (AOS)--a cilium-like structure emanating from the inner segment and running alongside the outer segment of photoreceptors--is described. The AOS occurs in both rods and cones of Poecilia reticulata. Its ultrastructure, including the arrangement of microtubules, which originate from the ciliary stalk, is the same in rods and cones. The cone-AOS is connected with the outer segment by a thin plasmabridge, whereaa the rod-AOS lies embedded within the outer segment. The outer segment of the cone, in contrast to that of the rod, is separated from the pigment epithelium by a large extracellular space. An intimate contact, however, is secured by the AOS; its membrane is closely appositioned to the pigment epithelium membrane. The functional significance of the AOS and its possible occurrence in other vertebrate classes, are discussed.