Mortality after surgery for primary hyperparathyroidism: results from a nationwide cohort.

BACKGROUND: Contemporary patients with primary hyperparathyroidism are often diagnosed with mildly raised serum calcium levels. Previous studies have reported increased mortality in patients with primary hyperparathyroidism. This retrospective cohort study aimed to examine whether contemporary patients operated for primary hyperparathyroidism have higher mortality than the general population, and whether mortality in these patients is associated with serum calcium concentration, adenoma weight or multiglandular disease. METHODS: Patients from a Swedish national cohort consisting of patients registered in the Scandinavian Quality Register for Thyroid, Parathyroid, and Adrenal Surgery 2003-2013, were matched with population controls. The National Patient Register, the Swedish Cause of Death Register, and socioeconomic data were cross-linked. End of follow-up was 10 years after surgery, 31 December 2015, or emigration. Mortality was analysed by standardized mortality ratio, Kaplan-Meier survival estimates, and univariable and multivariable Cox regression. Multiple imputation by chained equations was performed on missing data. RESULTS: After exclusions, there were 5009 patients with primary hyperparathyroidism and 14 983 controls. Multivariable Cox regression analysis adjusted for age, sex, Charlson Co-morbidity Index, marital status, level of education, disposable income, and period of surgery showed lower mortality in patients than controls (hazard ratio (HR) 0.83, 95 per cent c.i. 0.75 to 0.92). In univariable Cox regression of mortality in patients, serum calcium concentration (mmoles per litre) was associated with mortality (HR 2.20, 1.53 to 3.16). This association remained in multivariable Cox regression after multiple imputation (HR 1.79, 1.19 to 2.70). CONCLUSION: Mortality was not increased in patients operated for primary hyperparathyroidism compared with controls in a contemporary setting. Preoperative serum calcium concentration might, however, influence survival.

Roadmap to cellular reprogramming--manipulating transcriptional networks with DNA, RNA, proteins and small molecules.

Recent reports demonstrate that the plasticity of mammalian somatic cells is much higher than previously assumed and that ectopic expression of transcription factors may have the potential to induce the conversion of any cell type into another. Fibroblast cells can be converted into embryonic stem cell-like cells, neural cells, cardiomyocytes, macrophage-like cells as well as blood progenitors. Additionally, the conversion of astrocytes into neurons or neural stem cells into monocytes has been demonstrated. Nowadays, in the era of systems biology, continuously growing holistic data sets are providing increasing insights into core transcriptional networks and cellular signaling pathways. This knowledge enables cell biologists to understand how cellular fate is determined and how it could be manipulated. As a consequence for biomedical applications, it might be soon possible to convert patient specific somatic cells directly into desired transplantable other cell types. The clinical value, however, of such reprogrammed cells is currently limited due to the invasiveness of methods applied to induce reprogramming factor activity. This review will focus on experimental strategies to ectopically induce cell fate modulators. We will emphasize those strategies that enable efficient and robust overexpression of transcription factors by minimal genetic alterations of the host genome. Furthermore, we will discuss procedures devoid of any genomic manipulation, such as the direct delivery of mRNA, proteins, or the use of small molecules. By this, we aim to give a comprehensive overview on state of the art techniques that harbor the potential to generate safe reprogrammed cells for clinical applications.

Expression of matrix metalloproteinase-2 in glial and neuronal tumor cell lines: inverse correlation with proliferation rate.

The expression of matrix metalloproteinases (MMPs) has been found to be positively correlated to the degree of malignancy in gliomas, indicating that poorly differentiated brain tumor cells produce more MMPs than differentiated ones. We determined the production of active MMP-2 in five glial (U138MG, U373MG, A172, C6, GOS-3), two neuronal (SK-N-SH, SK-N-MC), and two pluripotent cell lines with facultative neuronal and glial differentiation (P19 and NT2) by gelatin zymography. The MMP-2 activity profiles were compared to the proliferative activities of the cell lines. MMP-2 expression varied from barely existent (P19 cells) to strong (U138MG and SK-N-SH). Interestingly, for the cell lines with high MMP-2 expression levels, low proliferative activities were recorded, and vice versa. Retinoic acid induced neuronal differentiation and a reduction of proliferation of P19 cells; the differentiated cells produced significantly more MMP-2 than untreated cells. Upon confluency, GOS-3 cells showed reduced proliferation, but increased MMP expression. Thus, proliferative activity was inversely correlated to MMP-2 expression in the tumor cell lines analyzed.

Migratory potential of transplantable neural tumor cell lines.

Experimentally induced primitive neuroectodermal tumor (PNET) cell lines were transplanted into neonatal and adult rat brain and examined neuropathologically for their tumorigenic potential. Both cell lines showed a striking migratory behavior in both neonatal and adult brain. Migration of tumor cells was found in host brain parenchyma, along white matter tracts and associated with CSF pathways. These neural tumor cell lines provide a valuable tool for the development of strategies against strongly migrating neural tumors.

Trophic effects of cardiotrophin-1 and interleukin-11 on rat dorsal root ganglion neurons in vitro.

Cardiotrophin-1 (CT-1) was originally isolated for its hypertrophy inducing effects on cardiac myocytes whereas interleukin-11 (IL-11) was identified due to its ability to stimulate an interleukin-6 (IL-6) dependent plasmocytoma cell line. Both cytokines are structurally and functionally related to a group of factors called neuropoietic cytokines, which also includes IL-6, ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), and oncostatin M. These factors have trophic effects on subsets of neurons. In the present study we examined the influence of CT-1 and IL-11 on newborn rat dorsal root ganglion neuron survival in vitro. Mouse CT-1 showed prominent trophic effects that were comparable to those of CNTF and LIF. Mouse IL-11 alone did not enhance neuronal survival, but soluble mouse IL-11 receptor alpha rendered neurons sensitive to IL-11. Surprisingly, soluble IL-11 receptor alpha even had slight neurotrophic effects by itself. These results suggest that CT-1 and IL-11 might also be involved in the physiological regulation of sensory neuron survival. Thus, they might, like CNTF, become tools for the therapeutic intervention in neurodegeneration due to disease, toxicity, and trauma.

Interleukin-6 (IL-6) and its soluble receptor support survival of sensory neurons.

The cytokine interleukin-6 (IL-6) has multiple functions in the immune and hematopoietic systems. IL-6 is related to ciliary neurotrophic factor (CNTF), a trophic factor for motoneurons, sensory dorsal root ganglion (DRG) neurons, and other neuronal subpopulations. Both act via related receptor complexes, consisting of one ligand-specific alpha-receptor subunit (IL-6R and CNTFR, respectively) and two signal-transducing receptor components. Even though IL-6 is expressed by neurons and glia, the functions of IL-6 in the nervous system are poorly understood. Here, we report that exogenous human IL-6 promotes the survival of dissociated newborn rat DRG neurons in vitro if supplemented with soluble human IL-6-alpha-receptor. The dosages of human IL-6 and soluble human IL-6R necessary to achieve neurotrophic effects could be reduced markedly by linking ligand and alpha-receptor component in a designer cytokine. Furthermore, we show that newborn rat DRG neurons express and secrete bioactive IL-6. Endogenously secreted IL-6 does not enhance survival of these neurons in vitro, suggesting that DRG neurons do not sufficiently express cell surface IL-6R. Exogenously added soluble rat IL-6R rendered DRG neurons responsive to secreted IL-6. Our results indicate an autocrine function of IL-6 in DRG neuron survival which depends on membrane-bound or soluble IL-6R as a neurotrophic cofactor.

Human CNTF and related cytokines: effects on DRG neurone survival.

Ciliary neurotrophic factor (CNTF), leukaemia inhibitory factor (LIF), oncostatin M (OSM), interleukin-6 (IL-6), and interleukin-11 (IL-11) are structurally and functionally related cytokines. We compared their survival-promoting activities on embryonic chick and newborn rat dorsal root ganglion (DRG) neurones. Human CNTF showed the well known trophic effect on both chick and rat DRG neurones. Human and murine LIF and, at unphysiologically high doses, human OSM were trophic for rat neurones, but failed to promote chick DRG cell survival. Human IL-11, murine IL-6 and human IL-6 did not improve chick or rat DRG neurone survival; soluble human IL-6 receptor alpha did not increase sensitivity to human IL-6. Thus, human CNTF as well as murine and human LIF had special neurotrophic properties compared with other related cytokines.

Human ciliary neurotrophic factor: a structure-function analysis.

Ciliary neurotrophic factor (CNTF) promotes survival in vitro and in vivo of several neuronal cell types including sensory and motor neurons. The primary structure of CNTF suggests it to be a cytosolic protein with strong similarity to the alpha-helical cytokine family which is characterized by a bundle of four anti-parallel helices. CNTF exerts its activity via complexation with CNTF receptor (CNTF-R). This complex consists of a CNTF-binding protein (CNTF-R) and two proteins important for signal transduction [gp130 and leukaemia inhibitory factor receptor (LIF-R)]. We have shortened the cDNA coding for CNTF at both the 5' and the 3' end and expressed the truncated proteins in bacteria. Biological activities of the protein preparations were determined by their ability to induce proliferation of BAF/3 cells that were stably transfected with CNTF-R, gp130 and LIF-R cDNAs. CNTF proteins with 14 amino acid residues removed from the N-terminus were biologically active whereas the removal of 23 amino acids resulted in an inactive protein. In addition, 18 amino acid residues could be removed from the C-terminus of the CNTF protein without apparent loss of bioactivity, but further truncation at the C-terminus yielded biologically inactive proteins. The introduction of two point mutations into the CNTF protein at a site that presumably interacts with one of the two signal-transducing proteins resulted in a CNTF mutant with no measurable bioactivity. In addition, a model of the three-dimensional structure of human CNTF was constructed using the recently established structural co-ordinates of the related cytokine, granulocyte colony-stimulating factor. CD spectra of CNTF together with our mutational analysis and our three-dimensional model fully support the view that CNTF belongs to the family of alpha-helical cytokines. It is expected that our results will facilitate the rational design of CNTF mutants with agonistic or antagonistic properties.

Site-directed mutagenesis of human CNTF: functional analysis of recombinant variants.

Ciliary neurotrophic factor (CNTF), interleukin-6 (IL-6), leukemia inhibitory factor (LIF), and oncostatin M (OSM) share functional properties, a predicted common helical framework, and partially identical receptor components. CNTF is a survival promoting factor for various types of neurons in vitro and in vivo. In the present study, structural features essential for the biological function of human CNTF were investigated. Several recombinant CNTF variants were constructed by PCR and expressed in E. coli. Their survival promoting activities were determined using cultures of embryonic chick and newborn rat dorsal root ganglion cells. Deletion of 14 N-terminal and 18 C-terminal amino acids significantly increased bioactivity compared to wild-type (wt) CNTF. Further truncation of the CNTF molecule at the N- or C-terminus resulted in a significant reduction or complete loss of activity. Substitution of two amino acids (Lys154Glu and Trp157Pro) abolished the survival promoting effect. Recently described analogous substitutions in IL-6 had resulted in a partial IL-6 receptor antagonist. However, the double substitution variant had no significant inhibitory effect on wtCNTF activity in assays with both wt and mutant factor. The CNTF variants constructed had almost identical effects on both chick and rat neurons indicating a close similarity of the avian and the mammalian CNTF receptor complex. The present results also demonstrate that a core segment of the CNTF molecule is indispensable for biological function. Analogous segments important for activity have already been identified in the related molecules IL-6, LIF, and OSM. Thus, our data confirm the close structural relationship of CNTF to these "neuropoietic" cytokines. In addition, they demonstrate that site-directed mutagenesis of recombinant human CNTF can yield molecules which show increased survival promoting activity on mammalian neurons.

[A pseudoelastic NiTi uprighting spring for the molars--its design, biomechanical testing and clinical use]. / Eine pseudoelastische NiTi-Aufrichtefeder für Molaren--Entwurf, biomechanische Prüfung und klinische Anwendung.

Uprighting inclined molars is one of the most common problems encountered in pre-restorative orthodontics. To prevent occlusal trauma, an intrusive force has to be applied to the molar in addition to the uprighting moment. Owing to their construction, current mechanical devices for uprighting either to not meet this requirement, or are difficult to adjust when in place. For this reason, an improved uprighting spring is described which utilizes the properties specific to super-elastic (pseudo-elastic) NiTi alloys. The most important property of super-elastic wires is the fact that they produce constant forces or moments within a specific deformation range. In order to utilize this useful property, certain design criteria have to be met. Recent measurements have shown that a super-elastic wire (Sentalloy, 0.016'' x 0.022'') having a length of 10 mm generates a constant moment of 7 to 8 Nmm within a bending angle of 50 degrees to 180 degrees. On the basis of these results, a table that permits the determination of the proper wire length needed to provide a constant moment within a given range of bending angles is proposed. The superelastic uprighting spring described here comprises an NiTi wire segment having a length of 7 mm and a mesial and distal steel wire segment. In the active state, the spring generates an uprighting moment of 8 Nmm and an intrusive force of 0.6 N. Numerical analysis using the finite element program, SOLF/MESY, and biomechanical testing with the orthodontic measuring and simulation system (OMSS) have shown that this force system remains stable throughout the entire uprighting process. The clinical application of the spring is demonstrated in a specific case.

An experimental apparatus for the simulation of three-dimensional movements in orthodontics.

An apparatus for the study of three-dimensional force systems and the resulting movements during orthodontic treatment is presented. The instrument consists of two force-torque transducers which are capable of recording both forces and torques simultaneously, in all spatial directions. Each sensor has a measuring range of 15N (450 Nmm) and a resolution of 0.02 N (0.5 Nmm) and is mounted on a set of three translational and three rotational stages driven by stepping motors. Positioning accuracy is in the range of 1 micron and 0.01 degrees respectively. The apparatus is computer controlled and supported by comprehensive software.

[Orthodontic measuring and simulating systems (OMSS) for the static and dynamic analysis of tooth movement]. / Orthodontisches Mess- und Simulationssystem (OMSS) für die statische und dynamische Analyse der Zahnbewegung.

An orthodontic measurement and simulation system (OMSS) is presented. The major components of this system are two measuring tables each comprising a force/torque sensor and a motor driven, fully three-dimensionally adjustable positioning stage. The force/torque sensors are capable of measuring simultaneously all forces and torques acting on a tooth. Using the computer program "OMSS" which runs on a personal computer, several different measurements can be conducted. On the one hand, the system supports absolute measurements such as the registration of a force/deflection diagram. Furthermore, even multidimensional force/deflection- or torque/distance curves can be measured. On the other hand, simulations of orthodontic tooth movement can be conducted. In such simulations, the force system acting on a tooth is measured and the resulting tooth movements are calculated. By using this "computer typodont", not only the static but the dynamic behaviour of orthodontic appliances can be studied. The application of this system is demonstrated by the analysis of several orthodontic problems.

Application of the orthodontic measurement and simulation system (OMSS) in orthodontics.

An orthodontic measurement and simulation system (OMSS) is introduced. The major component of the system consists of two force-moment sensors capable of measuring forces and moments in all three planes of space simultaneously. The two sensors are mounted on motor-driven positioning tables with full three-dimensional mobility. All mechanical components are built in a temperature-controlled chamber. A control programme executed by a personal computer performs various types of measurement which can be classified as absolute measurements (e.g. force-deflection diagrams) and simulations of orthodontic tooth movement. By using the OMSS any orthodontic problem at the level of a two-tooth model can be analysed statically and dynamically. Besides other applications, the study evaluates three mechanical systems available for uprighting molars, namely a straight wire, a conventional uprighting spring, and a modified Burstone uprighting spring. It was found that the force systems produced by the straight wire and by the conventional uprighting spring showed a severe extrusive force component which may lead to occlusal trauma. The uprighting performance of the straight wire was inadequate. The conventional uprighting spring produced a large uprighting moment (17.8 Nmm), but also a strong lingual tipping moment (1.5 Nmm). The modified Burstone loop showed the best static and dynamic performance. It produced a force system with substantial uprighting moments in both the sagittal (11.6 Nmm) and frontal plane (4.2 Nmm). A slight intrusive force (0.09 N) might prevent the development of occlusal trauma during treatment. However, concern should be addressed to the fact that intra-oral adjustment of this uprighting spring is difficult because of its high susceptibility to minor modifications of its geometry.

[The materials engineering characteristics of orthodontic nickel-titanium wires]. / Materialtechnische Besonderheiten orthodontischer Nickel-Titan-Drähte.

Since their introduction in 1971 nickel-titanium wires have been widely used in orthodontics. Today, there is a multitude of new NiTi-alloys, whose properties are described. Beside the memory effect, these alloys have particular elastic properties, which can be characterized by a low modulus of elasticity, excellent springback, and pseudoelasticity (superelasticity). These properties are a consequence of the fact that depending on temperature and mechanical stress NiTi-alloys have two crystalline structures: martensite and austenite. The transition between these two phases, called martensitic transformation, is responsible for the memory effect, where a one way and a two way effect can be distinguished. For orthodontic applications pseudoelasticity is regarded as a highly favourable property. Pseudoelastic behavior is caused by stress induced martensite. Analysing the elastic properties of the available wires two categories can be distinguished: "work hardened martensite" and "pseudoelastic alloy". The biocompatibility of NiTi is sufficient, it can be used as an implant material.