Exploiting Distributed, Heterogeneous and Sensitive Data Stocks while Maintaining the Owner's Data Sovereignty.

BACKGROUND: To achieve statistical significance in medical research, biological or data samples from several bio- or databanks often need to be complemented by those of other institutions. For that purpose, IT-based search services have been established to locate datasets matching a given set of criteria in databases distributed across several institutions. However, previous approaches require data owners to disclose information about their samples, raising a barrier for their participation in the network. OBJECTIVE: To devise a method to search distributed databases for datasets matching a given set of criteria while fully maintaining their owner's data sovereignty. METHODS: As a modification to traditional federated search services, we propose the decentral search, which allows the data owner a high degree of control. Relevant data are loaded into local bridgeheads, each under their owner's sovereignty. Researchers can formulate criteria sets along with a project proposal using a central search broker, which then notifies the bridgeheads. The criteria are, however, treated as an inquiry rather than a query: Instead of responding with results, bridgeheads notify their owner and wait for his/her decision regarding whether and what to answer based on the criteria set, the matching datasets and the specific project proposal. Without the owner's explicit consent, no data leaves his/her institution. RESULTS: The decentral search has been deployed in one of the six German Centers for Health Research, comprised of eleven university hospitals. In the process, compliance with German data protection regulations has been confirmed. The decentral search also marks the centerpiece of an open source registry software toolbox aiming to build a national registry of rare diseases in Germany. CONCLUSIONS: While the sacrifice of real-time answers impairs some use-cases, it leads to several beneficial side effects: improved data protection due to data parsimony, tolerance for incomplete data schema mappings and flexibility with regard to patient consent. Most importantly, as no datasets ever leave their institution, owners can reject projects without facing potential peer pressure. By its lower barrier for participation, a decentral search service is likely to attract a larger number of partners and to bring a researcher into contact with the right potential partners.

Age-related immunohistochemical and ultrastructural changes in rat oculomotor nerve.

During ageing process, multiple changes occur on nervous tissue composed of cells and extracellular matrix. Changes on nervous tissues are usually known as degenerative changes on axon structure and connective tissue covering the nerve such as a decrease in the number of fibre or general structural changes. For this purpose, we have studied age-dependent ultrastructural changes in the rat oculomotor nerve with electron microscopy and also demonstrated collagen structure of the neural sheaths with immunohistochemical techniques. This study was conducted in Gazi University Faculty of Medicine, Department of Anatomy with a total of nine Wistar albino rats. We observed strong collagen type I immunoreactivity in endoneurium and slight to moderate reactivity in fibroblast cytoplasm in 3-month- and 12-month-old groups and mild reactivity in 24-month-old group. Collagen type IV immunoreactivity was stronger in endoneurium and perineurium in the 3-month- and 12-month-old groups compared with collagen type I and fibroblast cytoplasm showed a very strong reactivity. On the other hand, in the 24-month-old group, there was slight reactivity in endoneurium and a strong reactivity in perineurium. NGF staining showed moderate to strong reactivity on Schwann cells of the 3-month-old group. The immunoreactivity decreased in the 12-month- and 24-month-old groups. In the 3-month-old rat group, Schwann cell cytoplasm, mitochondrial structure and neurofilaments were normal. In the 12-month-old group, there were no changes in organelle distribution, mitochondrial structure and neurofilaments, but there was an increase in the connective tissue. An inconsiderable number of degenerated myelinated nerves were observed. We detected an important decrease in the collagen type I immunoreactivity, which could suggest that the endoneurium, perineurium and epineurium are less resistant to the age-related collagen loss and that the peripheral nerve is protected by a weaker barrier in the old group. The collagen type IV immunoreactivity was significantly decreased with age. NGF synthesis decreases with age because of Schwann cell structural degeneration or for different reasons. Thus, this could explain the diminished capacity of regeneration and damage of the myelination of the peripheral nerve.

Branching patterns of rabbit oculomotor and trochlear nerves demonstrated by Sihler's stain technique.

A modified Sihler's stain technique was used to visualize the branching patterns of oculomotor and trochlear nerves. The levator palpebrae, superior rectus, inferior rectus, medial rectus, inferior oblique, superior oblique and tensor trochlea muscles were isolated from the eyes of normal rabbits and processed using modified Sihler's technique. The distributions and terminal ramifications of the oculomotor and trochlear nerves were observed. Two distinct divisions and terminal branches of the oculomotor nerve were shown in detail together with the trochlear nerve distribution. The application of Sihler's technique enables researchers to trace nerve branching within relatively transparent muscles, whereas the nerve fibers are counterstained and clearly visible. This technique could be useful for detailed studies of the motor control of extraocular muscles.

Neurocranial morphology as determined by asymmetries of the skull base.

The goal of the current study was to provide an easy to use criterion to diagnose neurocranial asymmetries. An anatomical survey of the external aspect of the skull base was planned to correlate with radiological studies. In a sample of 239 skulls, variations of the angular relationship between the structures seen on a basilar view of the cranium were analysed. An anterior and a posterior transverse line were plotted with respect to the midline. Departures from 90 degrees to the midline for either of the transverse lines were less than 5 degrees in normal skulls, between 5 degrees and 7 degrees in skulls classed by independent inspection as asymmetric, and more than 7 degrees in obviously malformed skulls.

Demonstration of congenital anomalies in the joints of the forelimbs and hindlimbs caused by several pharmacological agents.

In this study, fetal joint abnormalities caused by cytosine arabinoside, caffeine, sodium salicylate, and retinyl acetate administration during pregnancy, were investigated. In the cytosine-arabinoside-administered group, complete disappearance of joint spaces in the forelimbs, and narrowing or complete disappearance of joint spaces in the hindlimbs was highly noticeable. In the caffeine group, in all forelimb joints starting from art, humeri, there were abnormal fusions in bones, together with occasional disappearance of the joint space. In hindlimbs, similar findings were observed. In the sodium salicylate group, the complete disappearance of joint space and surfaces among humerus-radius and ulna was striking, and occasional fusions in tarsometatarsal joints were also present. Severe narrowing of the same joint space in the retinyl acetate group was striking. Total disappearance of the articulation manus and carpometacarpal joints was observed, together with hindlimb joint and bone findings.

Morphological analysis of the myocardial fiber architecture of ventriculus cordis in normal and malformed human hearts.

In this study, ten normal and one malformed adult human hearts obtained from the collections of Gazi University Department of Anatomy were investigated. Muscle maceration techniques of Romeis and Torrant-Guasp have been used. In the normal heart, the superficial layer of ventricular myocardium has been detected. Then, middle layer was demonstrated by lifting up the fibers of this layer. Endocardium of ventricles was dissected and inner layer was observed. Consequently, direction of muscle fibers was examined in ventricular myocardium. Sections of muscle samples from an hypertrophied heart were prepared by routine light microscopic procedures. In the normal heart, a thin middle layer was present in right ventricle. This layer was appeared to be hypertrophied in the malformed heart.

Occipital emissary foramen in skulls from central Anatolia.

In this study, a total of 125 female and 175 male adult human skulls from Central Anatolia were examined. The incidence and localization of the rate occipital foramen found on the squama of occipital bone were investigated. This foramen has significant importance during suboccipital craniotomies since it transmits the occipital emissary vein. In the present study, the occipital foramen was found in 8 (2.6%) skulls. Its location was closer to the foramen magnum but not to the external occipital protuberance.

The ultrastructure of the adrenal cortex of the Mongolian gerbil (M. unguiculatus).

Ultrastructurally, the adrenal cortex of the Mongolian gerbil can be divided into two main regions and one narrow interposed border zone. The outer region corresponds to the zona glomerulosa and zona fasciculata of the rat adrenal cortex, whereas the inner region corresponds to the rat zona reticularis. The mitochondria are variable in shape, size and internal structure but generally lamelliform or tubulo-vesicular with a dense matrix in the outer region and plate-like and tubular in the inner region. Some of the mitochondria in the border region are of the polylaminar membranous type. The endoplasmic reticulum is abundant and smooth in the outer region but less prominent in the inner regions, where it is both smooth and rough. The concentric whorled membranes of rough endoplasmic reticulum are a characteristic feature of the border zone. Lipid vacuoles are abundant in the outer region. Lysosomes are numerous in the inner region and tend to form groups of 4 or 5. Aminoglutethimide causes a less conspicuous alteration in the adrenal cortex of the Mongolian gerbil than in the rat. The main alterations consist of a profound increase of lipid and lysosomes, a decrease in the number of SER profiles, and complete disappearance of the whorled membranes of RER.