Finite element investigation of implant-supported fixed partial prosthesis in the premaxilla in immediately loaded and osseointegrated states

The aim of this study was to gain insight into the behaviour of the stresses and strains at the bone–implant interface of an implant-supported fixed partial prosthesis (FPP) in the premaxilla under immediate loading and osseointegrated conditions. Finite element models of a four-unit FPP were generated. An extreme condition was simulated, using only two immediately loaded implants in order to derive recommendations for possible clinical application. Straight and 20°-angled abutments and bonded or sliding contact between the bridge and abutment were simulated. In addition, two models were generated with two completely osseointegrated implants. A 150 N load to the prosthesis at a 45° angle to the long axis of each implant was applied. Minor differences were observed in implant displacements, stress and strain distributions of the two abutment designs. However, bone loading exceeded the physiological limits, including a risk of bone atrophy. A considerable decrease in implant displacements and bone loading was observed in the osseointegrated cases. An FPP supported by only two implants cannot be recommended for immediate loading.     

Pneumothorax after mediastinal emphysema. The site and mechanism of pleural rupture

By rupture of the mediastinal pleura a mediastinal emphysema may lead to a pneumothorax. An experiment imitating this process is able to point out two spots where the pleura is most likely to tear: An area as large as a thumb tip above the root of the left lung; there mediastinal pleura covers a space the width of which changes most in respirating. The border of a fatty fold based on the pericardium and covered by mediastinal pleura; it is there that maxima of tension occur by emphysematic inflation. In general, air from the mediastinum far more often enters the left pleural cavity than the right one.     

Margins and torsion of the human fibula

The borders and ridges of the fibula show a difficult aspect caused by the bone-forming musculature. These structures are an occasion for misunderstanding and mistaken denominations, which even had a noticeable effect on the PNA. Two thirds of all human fibulae exhibit a clearly prominent 'crista musculi tibialia posterioris', giving tendinuous attachment to the tibialis posterior muscle. In diagnosis of borders this crista may lead to errors, because it branches off from the interosseous border underneath the upper fourth of the fibula and reaches the medial crest in the middle of the bone. Most of the borders of the fibula show a twisted course corresponding to the direction of the shaping musculature and effecting a fictitious torsion of the shaft. The proper torsion of the fibula, however, is substantiated by the difference between the absolute torsion (= twist of the two ends of the bone) and the accompanying torsion (= twist enforced by the torsion of the tibia).     

Manual examination of so-called lumbosacral instability

By the manual test of the lumbosacral instability described by Eder and Tilscher we can never find out for certain whether the fifth lumbar vertebra can be shifted ventrally above the sacrum. Before this test the patient has to be turned over on to his side with hips flexed, which causes a ventral flexion (anteflexion) of the lumbosacral segment. During the test, however, the lumbosacral segment is forced to a dorsal flexion (retroflexion); therefore the spinous process of the fifth lumbar vertebra retires from the back surface simulating a sliding forward of the whole vertebra.     

Complexome analysis of the nitrite-dependent methanotroph Methylomirabilis lanthanidiphila

The atmospheric concentration of the potent greenhouse gases methane and nitrous oxide (N₂O) has increased drastically during the last century. Methylomirabilis bacteria can play an important role in controlling the emission of these two gases from natural ecosystems, by oxidizing methane to CO₂ and reducing nitrite to N₂ without producing N₂O. These bacteria have an anaerobic metabolism, but are proposed to possess an oxygen-dependent pathway for methane activation. Methylomirabilis bacteria reduce nitrite to NO, and are proposed to dismutate NO into O₂ and N₂ by a putative NO dismutase (NO-D). The O₂ produced in the cell can then be used to activate methane by a particulate methane monooxygenase. So far, the metabolic model of Methylomirabilis bacteria was based mainly on (meta)genomics and physiological experiments. Here we applied a complexome profiling approach to determine which of the proposed enzymes are actually expressed in Methylomirabilis lanthanidiphila. To validate the proposed metabolic model, we focused on enzymes involved in respiration, as well as nitrogen and carbon transformation. All complexes suggested to be involved in nitrite-dependent methane oxidation, were identified in M. lanthanidiphila, including the putative NO-D. Furthermore, several complexes involved in nitrate reduction/nitrite oxidation and NO reduction were detected, which likely play a role in detoxification and redox homeostasis. In conclusion, complexome profiling validated the expression and composition of enzymes hypothesized to be involved in the energy, methane and nitrogen metabolism of M. lanthanidiphila, thereby further corroborating their unique metabolism involved in the environmentally relevant process of nitrite-dependent methane oxidation.     

Activation of the GLP-1 Receptors in the Nucleus of the Solitary Tract Reduces Food Reward Behavior and Targets the Mesolimbic System

The gut/brain peptide, glucagon like peptide 1 (GLP-1), suppresses food intake by acting on receptors located in key energy balance regulating CNS areas, the hypothalamus or the hindbrain. Moreover, GLP-1 can reduce reward derived from food and motivation to obtain food by acting on its mesolimbic receptors. Together these data suggest a neuroanatomical segregation between homeostatic and reward effects of GLP-1. Here we aim to challenge this view and hypothesize that GLP-1 can regulate food reward behavior by acting directly on the hindbrain, the nucleus of the solitary tract (NTS), GLP-1 receptors (GLP-1R). Using two models of food reward, sucrose progressive ratio operant conditioning and conditioned place preference for food in rats, we show that intra-NTS microinjections of GLP-1 or Exendin-4, a stable analogue of GLP-1, inhibit food reward behavior. When the rats were given a choice between palatable food and chow, intra-NTS Exendin-4 treatment preferentially reduced intake of palatable food but not chow. However, chow intake and body weight were reduced by the NTS GLP-1R activation if chow was offered alone. The NTS GLP-1 activation did not alter general locomotor activity and did not induce nausea, measured by PICA. We further show that GLP-1 fibers are in close apposition to the NTS noradrenergic neurons, which were previously shown to provide a monosynaptic connection between the NTS and the mesolimbic system. Central GLP-1R activation also increased NTS expression of dopamine-β-hydroxylase, a key enzyme in noradrenaline synthesis, indicating a biological link between these two systems. Moreover, NTS GLP-1R activation altered the expression of dopamine-related genes in the ventral tegmental area. These data reveal a food reward-suppressing role of the NTS GLP-1R and indicate that the neurobiological targets underlying food reward control are not limited to the mesolimbic system, instead they are distributed throughout the CNS.