Karsten Hufendiek

Gray matter alterations in visual cortex of patients with loss of central vision due to hereditary retinal dystrophies.

In patients with central visual field scotomata a large part of visual cortex is not adequately stimulated. Over time this lack of input could lead to a reduction of gray matter in the affected cortical areas. We used Voxel Based Morphometry to investigate structural brain changes in patients with central scotomata due to hereditary retinal dystrophies and compared their results to those of normal sighted subjects. Additionally we correlated clinical and demographic characteristics like duration of disease, scotoma size, visual acuity, fixation stability and reading speed to the amount of gray matter in whole brain analyses within the patient group. We found a decrease in gray matter around the lesion projection zone in visual cortex of patients in comparison to controls. Gray matter loss along the posterior and middle portions of the calcarine sulcus is also correlated with scotoma size, indicating that indeed the lack of functional input provokes the gray matter alterations. In whole brain regression analyses within the patient group we found an additional cluster in the right superior and middle frontal gyri, slightly anterior to the frontal eye fields, where gray matter correlated positively with fixation stability. This could be regarded as a consequence of oculomotor learning.

Mutation Spectrum of the ABCA4 Gene in 335 Stargardt Disease Patients From a Multicenter German Cohort—Impact of Selected Deep Intronic Variants and Common SNPs

Purpose Stargardt disease (STGD1) is an autosomal recessive retinopathy, caused by mutations in the retina-specific ATP-binding cassette transporter (ABCA4) gene. To establish the mutational spectrum and to assess effects of selected deep intronic and common genetic variants on disease, we performed a comprehensive sequence analysis in a large cohort of German STGD1 patients. Methods DNA samples of 335 STGD1 patients were analyzed for ABCA4 mutations in its 50 coding exons and adjacent intronic sequences by resequencing array technology or next generation sequencing (NGS). Parts of intron 30 and 36 were screened by Sanger chain-terminating dideoxynucleotide sequencing. An in vitro splicing assay was used to test selected variants for their splicing behavior. By logistic regression analysis we assessed the association of common ABCA4 alleles while a multivariate logistic regression model calculated a genetic risk score (GRS). Results Our analysis identified 148 pathogenic or likely pathogenic mutations, of which 48 constitute so far unpublished ABCA4-associated disease alleles. Four rare deep intronic variants were found once in 472 alleles analyzed. In addition, we identified six risk-modulating common variants. Genetic risk score estimates suggest that defined common ABCA4 variants influence disease risk in carriers of a single pathogenic ABCA4 allele. Conclusions Our study adds to the mutational spectrum of the ABCA4 gene. Moreover, in our cohort, deep intronic variants in intron 30 and 36 likely play no or only a minor role in disease pathology. Of note, our findings demonstrate a possible modifying effect of common sequence variants on ABCA4-associated disease.

Functional and structural brain modifications induced by oculomotor training in patients with age-related macular degeneration

Patients with age-related macular degeneration (AMD) are reliant on their peripheral visual field. Oculomotor training can help them to find the best area on intact peripheral retina and to efficiently stabilize eccentric fixation. In this study, nine patients with AMD were trained over a period of 6 months using oculomotor training protocols to improve fixation stability. They were followed over an additional period of 6 months, where they completed an auditory memory training as a sham training. In this cross-over design five patients started with the sham training and four with the oculomotor training. Seven healthy age-matched subjects, who did not take part in any training procedure, served as controls. During the 6 months of training the AMD subjects and the control group took part in three functional and structural magnetic resonance imaging (MRI) sessions to assess training-related changes in the brain function and structure. The sham-training phase was accompanied by two more fMRI measurements, resulting in five MRI sessions at intervals of 3 months for all participants. Despite substantial variability in the training effects, on average, AMD patients benefited from the training measurements as indexed by significant improvements in their fixation stability, visual acuity, and reading speed. The patients showed a significant positive correlation between brain activation changes and improvements in fixation stability in the visual cortex during training. These correlations were less pronounced on the long-term after training had ceased. We also found a significant increase in gray and white matter in the posterior cerebellum after training in the patient group. Our results show that functional and structural brain changes can be associated, at least on the short-term, with benefits of oculomotor and/or reading training in patients with central scotomata resulting from AMD.

Primary skeletal muscle cells cultured on gelatin bead microcarriers develop structural and biochemical features characteristic of adult skeletal muscle

A primary skeletal muscle cell culture, in which myoblasts derived from newborn rabbit hindlimb muscles grow on gelatin bead microcarriers in suspension and differentiate into myotubes, has been established previously. In the course of differentiation and beginning spontaneous contractions, these multinucleated myotubes do not detach from their support. Here, we describe the development of the primary myotubes with respect to their ultrastructural differentiation. Scanning electron microscopy reveals that myotubes not only grow around the surface of one carrier bead but also attach themselves to neighboring carriers, forming bridges between carriers. Transmission electron microscopy demonstrates highly ordered myofibrils, T‐tubules, and sarcoplasmic reticulum. The functionality of the contractile apparatus is evidenced by contractile activity that occurs spontaneously or can be elicited by electrostimulation. Creatine kinase activity increases steadily until day 20 of culture. Regarding the expression of isoforms of myosin heavy chains (MHC), we could demonstrate that from day 16 on, no non‐adult MHC isoform mRNAs are present. Instead, on day 28 the myotubes express predominantly adult fast MHCIId/x mRNA and protein. This MHC pattern resembles that of fast muscles of adult rabbits. In contrast, primary myotubes grown on matrigel‐covered culture dishes express substantial amounts of non‐adult MHC protein even on day 21. To conclude, primary myotubes grown on microcarriers in their later stages exhibit many features of adult skeletal muscle and characteristics of fast type II fibers. Thus, the culture represents an excellent model of adult fast skeletal muscle, for example, when investigating molecular mechanisms of fast‐to‐slow fiber‐type transformation.

Trajectory-guided biopsy of orbital tumor – Technology, principal considerations and clinical implementation

Intraorbital space-occupying lesions always pose a challenge, both in terms of definite surgical removal as well as preoperative sampling for histopathological examination. Despite the use of modern high-resolution imaging techniques, the dignity of orbital lesions can often not be determined with sufficient certainty preoperatively. As the amount and complexity of treatment possibilities continue to increase, detailed diagnostics in advance of treatment choice are essential. Histological classification of orbital lesions can still be considered the gold standard for reliable diagnoses, leading to appropriate treatment. Over recent years minimally invasive surgical approaches have gained more importance in the treatment and diagnosis of cranio-maxillo-facial tumor and trauma. The aim of our study was to adapt and establish a precise procedure for orbital biopsies. 23 patients suffering from space-occupying lesions of unknown dignity were included. Trajectory-guided procedures were pre-planned for all cases. In most cases minimally invasive procedures were suitable for taking biopsies of the orbit. For only two patients a conventional, non-minimally invasive, lateral orbitotomy had to be performed. Further evaluation of the presented procedure demonstrates clearly that trajectory-guided biopsies of the orbit can be performed correctly and effectively, regardless of the suspected lesions size.

[Orbital complication of acute sinusitis : Orbital cellulitis in a 10-year-old child].

Bacterial orbital cellulitis is a life-threatening infection of the postseptal orbital tissue. It can occur in the context of sinusitis, particularly in children and adolescents. Ocular complications include exposure keratopathy, increased intraocular pressure, occlusion of the central retinal artery or vein and optic neuropathy. Rarely, a subperiosteal abscess can occur, and osteomyelitis can lead to spread of the infection to the cerebrum. A rapid diagnosis and targeted therapy are essential for saving the eye as well as the life of the patient.ZusammenfassungDie bakterielle Orbitaphlegmone ist eine lebensbedrohliche Infektion des postseptalen Orbitagewebes. Sie kann im Rahmen einer Sinusitis insbesondere bei Kindern und Jugendlichen auftreten. Zu den okulären Komplikationen gehören die Expositionskeratopathie, erhöhter Intraokulardruck, Verschluss der Zentralarterie oder -vene sowie die Optikusneuropathie. Selten kann es zum subperiostalen Abszess und über eine Osteomyelitis zum Übergreifen auf das Cerebrum kommen. Rasche Diagnosestellung und zielgerichtete Therapie sind sowohl für den funktionellen Organerhalt als auch quoad vitam essenziell.AbstractBacterial orbital cellulitis is a life-threatening infection of the postseptal orbital tissue. It can occur in the context of sinusitis, particularly in children and adolescents. Ocular complications include exposure keratopathy, increased intraocular pressure, occlusion of the central retinal artery or vein and optic neuropathy. Rarely, a subperiosteal abscess can occur, and osteomyelitis can lead to spread of the infection to the cerebrum. A rapid diagnosis and targeted therapy are essential for saving the eye as well as the life of the patient.