[Familial exsudative vitreoretinopathy (FEVR) in childhood]. / Familiäre exsudative Vitreoretinopathie (FEVR) im Kindesalter.

A case of secondary neovascularization of the optic disc in familial exsudative vitreoretinopathy (FEVR) is reported. A 12-year-old girl presented with decreased visual acuity of the right eye to 0.05. Funduscopy showed a prominent fibrovascular neovascularization of the optic disc covering the macula. Fluorescein angiography demonstrated circular peripheral ischemia as well as vascular anomalies in both eyes. Peripheral laser coagulation of the ischemic retina of the right eye was conducted with the patient under general anesthesia. The central neovascularization regressed and visual acuity increased up to 0.4. Molecular genetic examination detected the LRP5 gene for FEVR.

Graphical user interface for a robotic workstation in a surgical environment.

Surgery using a robotic system has proven to have significant potential but is still a highly challenging task for the surgeon. An eye surgery assistant has been developed to eliminate the problem of tremor caused by human motions endangering the outcome of ophthalmic surgery. In order to exploit the full potential of the robot and improve the workflow of the surgeon, providing the ability to change control parameters live in the system as well as the ability to connect additional ancillary systems is necessary. Additionally the surgeon should always be able to get an overview over the status of all systems with a quick glance. Therefore a workstation has been built. The contribution of this paper is the design and the implementation of an intuitive graphical user interface for this workstation. The interface has been designed with feedback from surgeons and technical staff in order to ensure its usability in a surgical environment. Furthermore, the system was designed with the intent of supporting additional systems with minimal additional effort.

Haptic interface for robot-assisted ophthalmic surgery.

Vitreo-retinal surgery is challenging, as delicate structures have to be manipulated. Eliminating tremor caused by human motions when doing micromanipulation can therefore improve the outcome of such an intervention. An eye surgery robot has been built to overcome this problem. The contribution of this paper is the design of a telemanipulation setup for the robotic system. A telemanipulation setup using a haptic device featuring force feedback as a user interface for controlling a hybrid parallel-serial micromanipulator is designed and developed. The position error control scheme is chosen and different control modes are provided. The output forces of the haptic device are analyzed. The system allows the surgeon to perform precise and comfortable micromanipulation. Nevertheless a way to provide more meaningful force feedback still has to be found.

The introduction of a new robot for assistance in ophthalmic surgery.

This paper introduces the design and development of a new robotic system to assist surgeons performing ophthalmic surgeries. The robot itself is very compact and similar to an average human hand in size. Its primary application is intraocular micromanipulation in order to overcome the existing challenges in treatment of diseases like Retinal Vein Occlusion (RVO). The novel hybrid mechanism designed for this robot allows microscale motions and is stable in the presence of vibrations common in operation room (OR). The robotic system can be easily integrated into standard operation rooms and does not require modification of conventional surgical tools. This compact microsurgical system is suitable for mounting on the patient's head and thereby, solves the problem of patient motion. The compatibility of the robotic system with a real world surgical setup was evaluated and confirmed in this work.

[Loss of visual acuity after treatment with pipamperone]. / Visusminderung nach Pipamperon-Therapie.

The butyrophenone derivative pipamperone is a neuroleptic agent administered to reduce psychomotor agitation and psychotic conditions in schizophrenic psychoses. Among other things it blocks D2 receptors in the dopamine pathways of the mesolimbic system and therefore reduces excess release of dopamine in the area thought to control psychotic experiences. Dopamine also takes part in signal transduction in the visual process. Loss of visual acuity, color vision, scotoma and electrophysiological alterations were observed under treatment with different groups of neuroleptics which interfere with dopamine metabolism but have not yet been observed after therapy with pipamperone. We present the case of a young women suffering from unilateral loss of visual acuity after treatment with pipamperone.

[In vivo confocal microscopy in blepharitis]. / Konfokale In-vivo-Mikroskopie bei Blepharitis.

BACKGROUND: Dysfunction of the meibomian glands with inflammation and obstruction has been suggested to be an important factor in the pathogenesis of chronic blepharitis. Few objective tests are, however, available to examine the meibomian glands directly. PATIENTS AND METHODS: Nineteen patients with anterior blepharitis, meibomitis, meibomian gland dysfunction or severe keratoconjunctivitis sicca associated with blepharitis as well as 10 patients with normal lid margins were examined with the HRTII/RCM in vivo confocal microscope. Scans of the tear film, the tarsal conjunctiva, the hair follicles and the meibomian glands were analysed by a masked observer. RESULTS: Patients with normal lid margins exhibited a minimal round cell infiltrate in the tarsal conjunctival epithelium and largely normal ducts of the meibomian glands lined with a multilayered epithelium as well as normal gland acini. In patients with anterior blepharitis, blepharitis associated with autoimmune peripheral ulcerative keratitis and blepharitis in the context of severe dry eye, confocal microscopy disclosed normal meibomian glands. In 12 patients with blepharitis/meibomitis or meibomian gland dysfunction, profound pathology was visible with dilatation and obstruction of the meibomian gland ducts. In 15 of 19 patients with blepharitis/meibomitis, but not in meibomian gland dysfunction, an intense inflammation was observed in the tarsal conjunctival epithelium and stroma. In one patient, demodex folliculorum was evident in vivo. In patients with normal lid margins as well as in patients with blepharitis, hair follicles appeared within normal limits. CONCLUSIONS: In vivo confocal microscopy allowed the examination of the tear film, the tarsal conjunctiva, the lid margin including the lash follicles and the meibomian glands. In patients with meibomian gland disease pathological changes could be visualised and documented objectively. The presence of an inflammatory infiltrate permitted us to differentiate between meibomitis and meibomian gland dysfunction. Changes of the lash follicles do not seem to play an important role in blepharitis. Thus, in vivo confocal microscopy represents an objective technique in the classification and follow-up of patients with blepharitis.

HNF4beta, a new gene of the HNF4 family with distinct activation and expression profiles in oogenesis and embryogenesis of Xenopus laevis.

The transcription factor hepatocyte nuclear factor 4 (HNF4) is an orphan member of the nuclear receptor superfamily expressed in mammals in liver, kidney, and the digestive tract. Recently, we isolated the Xenopus homolog of mammalian HNF4 and revealed that it is not only a tissue-specific transcription factor but also a maternal component of the Xenopus egg and distributed within an animal-to-vegetal gradient. We speculate that this gradient cooperates with the vegetally localized embryonic induction factor activin A to activate expression of HNF1alpha, a tissue-specific transcription factor with an expression pattern overlapping that of HNF4. We have now identified a second Xenopus HNF4 gene, which is more distantly related to mammalian HNF4 than the previously isolated gene. This new gene was named HNF4beta to distinguish it from the known HNF4 gene, which is now called HNF4alpha. By reverse transcription-PCR, we detected within the 5' untranslated region of HNF4beta two splice variants (HNF4beta2 and HNF4beta3) with additional exons, which seem to affect RNA stability. HNF4beta is a functional transcription factor acting sequence specifically on HNF4 binding sites known for HNF4alpha, but it seems to have a lower DNA binding activity and is a weaker transactivator than the alpha isoform. Furthermore, the two factors differ with respect to tissue distribution in adult frogs: whereas HNF4alpha is expressed in liver and kidney, HNF4beta is expressed in addition in stomach, intestine, lung, ovary, and testis. Both factors are maternal proteins and present at constant levels throughout embryogenesis. However, using reverse transcription-PCR, we found the RNA levels to change substantially: whereas HNF4alpha is expressed early during oogenesis and is absent in the egg, HNF4beta is first detected in the latest stage of oogenesis, and transcripts are present in the egg and early cleavage stages. Furthermore, zygotic HNF4alpha transcripts appear in early gastrula and accumulate during further embryogenesis, whereas HNF4beta mRNA transiently appears during gastrulation before it accumulates again at the tail bud stage. All of these distinct characteristics of the newly identified HNF4 protein imply that the alpha and beta isoform have different functions in development and in adult tissues.

Regulation and function of the tissue-specific transcription factor HNF1 alpha (LFB1) during Xenopus development.

We review the data available on the structure, developmental appearance and embryonic regulation of the tissue-specific transcription factor HNF1 alpha (LFB1) in Xenopus. The expression of the HNF1 alpha gene starts early in embryogenesis shortly after mid-blastula transition and the protein accumulates in the region of the embryo where liver, pronephros and gut--tissues that contain HNF1 alpha in the adult--are developing. The cofactor DCoH, known to stabilize dimer formation of HNF1 alpha, is present as a maternal factor in the egg and has a partially distinct tissue distribution compared to HNF1 alpha. This implies that DCoH does not only modulate HNF1 alpha dimerization but may also cooperate with other transcription factors. By injecting HNF1 alpha promoter CAT constructs into fertilized Xenopus eggs we obtained activation of the injected gene restricted to the region of the developing larvae expressing endogenous HNF1 alpha. Deletion analysis allowed to define the OZ-element that is essential for embryonic activation. This element also occurs in other promoters activated at mid-blastula transition in the embryo and interacts with the maternal factor OZ-1. As the HNF1 alpha promoter also contains functional binding sites for HNF4 and HNF1, we postulate that all of these transcription factors contribute to the cascade leading to proper embryonic activation of the HNF1 alpha gene.

Transcriptional hierarchy in Xenopus embryogenesis: HNF4 a maternal factor involved in the developmental activation of the gene encoding the tissue specific transcription factor HNF1 alpha (LFB1).

The tissue specific transcription factor HNF1 alpha (LFB1) expressed in liver, kidney, stomach and gut gets transcriptionally activated in Xenopus shortly after zygotic transcription starts. By microinjection into fertilized Xenopus eggs, a HNF1 alpha promoter fragment is activated in the middle part of developing larvae, reflecting the activation pattern of the endogenous HNF1 alpha gene. Mutational analysis of the HNF1 alpha promoter shows that HNF1 and HNF4 binding sites are essential for proper embryonic regulation. Since by injecting HNF4 mRNA into fertilized eggs the endogenous HNF1 alpha gene is activated ectopically and HNF4 is present as a maternal protein within an animal to vegetal gradient in the embryo, we assume that HNF4 initiates a transcriptional hierarchy involved in determination of different cell fates.

Genomic structure of the Xenopus laevis liver transcription factor LFB1.

Liver factor B1 [LFB1, also called hepatocyte nuclear factor 1 (HNF1)] is a tissue-specific vertebrate transcription factor that is present in the liver, intestine, stomach and kidney. The LFB1 protein contains an unusual homeobox that is characterized by an insertion of 21 amino acids (aa) not found in any other homeodomain protein. We have isolated and characterized the genomic sequences encoding the LFB1 of Xenopus laevis. By comparing the genomic sequences with the cDNA clones, we could identify nine exons. In general, the position of the introns is identical to the one previously found in the rat. However, the C-terminal activation domain of LFB1 contains, in each species, an exon that is split in two in the other species. The homeobox of the X. laevis LFB1 contains an intron at exactly the position where the 21 aa typical for LFB1 are inserted. This is in agreement with the structure found in the rat gene and supports the notion that the LFB1 homeobox evolved separately from the other genes encoding homeodomain proteins.

Elements and factors involved in tissue-specific and embryonic expression of the liver transcription factor LFB1 in Xenopus laevis.

LFB1 (HNF1) is a tissue-specific transcription factor found in the livers, stomachs, intestines, and kidneys of vertebrates. By analyzing the promoter of the Xenopus LFB1 gene, we identified potential autoregulation by LFB1 and regulation by HNF4, a transcription factor with a tissue distribution similar to that of LFB1. Injection of LFB1 promoter-chloramphenicol acetyltransferase constructs into Xenopus eggs revealed embryonic activation that is restricted to the region of the developing larvae expressing endogeneous LFB1. Proper embryonic activation was also observed with a rat LFB1 promoter. Deletion analysis of the Xenopus and rat promoters revealed that in both promoters embryonic activation is absolutely dependnet on the presence of an element that contains CCNCTCTC as the core consensus sequence. Since this element is recognized by the maternal factor OZ-1 previously described by N. Ovsenek, A. M. Zorn, and P. A. Krieg (Development 115:649-655, 1992), we might have identified the main constituents of a hierarchy that leads via LFB1 to the activation of tissue-specific genes during embryogenesis.

Developmental regulation and tissue distribution of the liver transcription factor LFB1 (HNF1) in Xenopus laevis.

The transcription factor LFB1 (HNF1) was initially identified as a regulator of liver-specific gene expression in mammals. It interacts with the promoter element HP1, which is functionally conserved between mammals and amphibians, suggesting that a homologous factor, XLFB1, also exists in Xenopus laevis. To study the role of LFB1 in early development, we isolated two groups of cDNAs coding for this factor from a Xenopus liver cDNA library by using a rat LFB1 cDNA probe. A comparison of the primary structures of the Xenopus and mammalian proteins shows that the myosin-like dimerization helix, the POU-A-related domain, the homeo-domain-related region, and the serine/threonine-rich activation domain are conserved between X. laevis and mammals, suggesting that all these features typical for LFB1 are essential for function. Using monoclonal antibodies, we demonstrate that XLFB1 is present not only in the liver but also in the stomach, intestine, colon, and kidney. In an analysis of the expression of XLFB1 in the developing Xenopus embryo, XLFB1 transcripts appear at the gastrula stage. The XLFB1 protein can be identified in regions of the embryo in which the liver diverticulum, stomach, gut, and pronephros are localized. The early appearance of XLFB1 expression during embryogenesis suggests that the tissue-specific transcription factor XLFB1 is involved in the determination and/or differentiation of specific cell types during organogenesis.