Gaze direction affects walking speed when using a self-paced treadmill with a virtual reality environment.

BACKGROUND: In a previous study it was observed that participants increase their walking speed during a dual task while walking on a self-paced treadmill in a virtual reality (VR) environment (Gait Real time Analysis Interactive Lab (GRAIL)). This observation is in contrast with the limited resources hypothesis, which suggests walking speed of healthy persons to decrease when performing a cognitive dual task. AIM: The aim of the present study was therefore to determine whether the cognitive demand of the task, an aroused feeling, discrepancy in optic flow or a change in gaze direction caused participants to walk faster in this computer assisted rehabilitation environment. MATERIALS: The GRAIL included a self-paced treadmill, a motion-capture system and synchronized VR environments. METHODS: Thirteen healthy young adults (mean age 21.6 ±â€¯2.5) were included in this study. Participants walked on the self-paced treadmill while seven different intervention conditions (IC) were offered. Prior to each IC, a control condition (CC) was used to determine the natural self-selected walking speed. Walking speed during the last 30 s of each IC was compared with the walking speed during the last 30 s of the preceding CC. RESULTS: Results show that the height on which a visual task was presented in the VR environment, influenced walking speed. Participants walked faster when gaze was directed above the focus of expansion. SIGNIFICANCE: These findings contribute to a further understanding of the differences between walking in a real life environment or computer assisted rehabilitation environment. When analyzing gait on a self-paced treadmill in the future, one must be attentive where to place a visual stimulus in the VR environment.

Quantification of Phosphatidylinositol Phosphate Species in Purified Membranes.

Phosphoinositide lipids (PIPs) are required for various processes during macroautophagy, such as phagophore formation and autophagosome-lysosome fusion. Hence, quantification of the seven PIP species in autophagosome membranes is an important tool to understand how these lipids govern the transition of autophagosomes into autolysosomes. Here, we describe microscopic and mass spectrometry methods which, although designed to quantify the different PIP species on purified lysosomes, can also be applied to analyze autophagosomal PIPs.

Rsk2, the Kinase Mutated in Coffin-Lowry Syndrome, Controls Cementum Formation.

The ribosomal S6 kinase RSK2 is essential for osteoblast function, and inactivating mutations of RSK2 cause osteopenia in humans with Coffin-Lowry syndrome (CLS). Alveolar bone loss and premature tooth exfoliation are also consistently reported symptoms in CLS patients; however, the pathophysiologic mechanisms are unclear. Therefore, aiming to identify the functional relevance of Rsk2 for tooth development, we analyzed Rsk2-deficient mice. Here, we show that Rsk2 is a critical regulator of cementoblast function. Immunohistochemistry, histology, micro-computed tomography imaging, quantitative backscattered electron imaging, and in vitro assays revealed that Rsk2 is activated in cementoblasts and is necessary for proper acellular cementum formation. Cementum hypoplasia that is observed in Rsk2-deficient mice causes detachment and disorganization of the periodontal ligament and was associated with significant alveolar bone loss with age. Moreover, Rsk2-deficient mice display hypomineralization of cellular cementum with accumulation of nonmineralized cementoid. In agreement, treatment of the cementoblast cell line OCCM-30 with a Rsk inhibitor reduces formation of mineralization nodules and decreases the expression of cementum markers. Western blot analyses based on antibodies against Rsk1, Rsk2, and an activated form of the 2 kinases confirmed that Rsk2 is expressed and activated in differentiating OCCM-30 cells. To discriminate between periodontal bone loss and systemic bone loss, we additionally crossed Rsk2-deficient mice with transgenic mice overexpressing the osteoanabolic transcription factor Fra1. Fra1 overexpression clearly increases systemic bone volume in Rsk2-deficient mice but does not protect from alveolar bone loss. Our results indicate that cell autonomous cementum defects are causing early tooth loss in CLS patients. Moreover, we identify Rsk2 as a nonredundant regulator of cementum homeostasis, alveolar bone maintenance, and periodontal health, with all these features being independent of Rsk2 function in systemic bone formation.

Effects of extracellular phosphate on gene expression in murine osteoblasts.

That phosphate homeostasis is tightly linked to skeletal mineralization is probably best underscored by the fact that the phosphaturic hormone FGF23 is primarily expressed by terminally differentiated osteoblasts/osteocytes and that increased circulating FGF23 levels are causative for different types of hypophosphatemic rickets. In contrast, FGF23 inactivation results in hyperphosphatemia, and unexpectedly this phenotype is associated with severe osteomalacia in Fgf23-deficient mice. In this context it is interesting that different cell types have been shown to respond to extracellular phosphate, thereby raising the concept that phosphate can act as a signaling molecule. To identify phosphate-responsive genes in primary murine osteoblasts we performed genome wide expression analysis with cells maintained in medium containing either 1 or 4 mM sodium phosphate for 6 h. As confirmed by qRT-PCR, this analysis revealed that several known osteoblast differentiation markers (Bglap, Ibsp, and Phex) were unaffected by raising extracellular phosphate levels. In contrast, we found that the expression of Enpp1 and Ank, two genes encoding inhibitors of matrix mineralization, was induced by extracellular phosphate, while the expression of Sost and Dkk1, two genes encoding inhibitors of bone formation, was negatively regulated. The ability of osteoblasts to respond to extracellular phosphate was dependent on their differentiation state, and shRNA-dependent repression of the phosphate transporter Slc20a1 in MC3T3-E1 cells partially abolished their molecular response to phosphate. Taken together, our results provide further evidence for a role of extracellular phosphate as a signaling molecule and raise the possibility that severe hyperphosphatemia can negatively affect skeletal mineralization.

[Jejunal intussusception of an inflammatory fibrinoid polyp]. / Jejunale Invagination eines inflammatorischen fibrinoiden Polypen.

Intussusception of parts of the intestine in adulthood is a rare cause of ileus. In more than 90 % of all cases there is a malignant or benign tumour situated in the parts of the intestine affected. We describe a 55-year-old patient who was admitted to hospital as an emergency because of signs of a proximal intestinal obstruction. Abdominal sonography suggested the diagnosis of a typical jejunal intussusception, whereas gastroscopy yielded no pathological findings. Laparotomy was performed immediately and confirmed the diagnosis. After intraoperative de-invagination 9 cm of jejunum and an inflammatory fibrinoid polyp of 3 cm were resected.

[Bone scintigraphy and clinical outcome in rheumatoid gonarthritis].

AIM: For evaluation of the effect of radiosynoviorthesis (RSO) on the early and delayed uptake of (99m)Tc-biphosphonates and its relation to clinical outcome we studied these variables before and after radiosynoviorthesis performed on 41 knees affected by rheumatoid arthritis. METHOD: Thirty-seven patients with rheumatoid gonarthritis were treated by intraarticular injection with 185 MBq yttrium-90 citrate. In four of them both knees were treated so that 41 therapies were evaluated. On the average 35 days before and 120 days after radiosynoviorthesis, the early and delayed uptake of (99m)Tc-diphosphonate (DPD) was measured with a planar gamma camera. Early and late DPD uptake was quantified as a ratio between count values derived from rectangular ROIs placed on the knee treated and on the ipsilateral thigh. The severity of clinical symptoms was assessed on two 3-point rating scales averaged. RESULTS: 30 of the 41 cases favorably responded to radiosynoviorthesis. There was a significant correlation between clinical outcome and pretherapeutic early DPD uptake (EDU) (p<0.05), but not between outcome and pretherapeutic late DPD uptake (DDU). In the whole group, EDU decreased in approximately 76% of cases after therapy (p<0.05), DDU in 54% (p>0.05). In 25 of the 30 responders EDU decreased; EDU increased or remained constant in five of the eleven non-responders. The correlation between outcome and the difference in EDU was significant (r = 0.344; p<0.05). There was no such significant relationship between the difference between pre- and posttherapeutic DDU and clinical course. CONCLUSION: Three-phase bone scintigraphy may contribute to predict and assess the success of radiosynovior-thesis in rheumatoid arthritis of the knee joint.

[Problems in the discontinuation of sterility treatment]. / Probleme des Abbruchs der Sterilitätsbehandlung.

In the period from 1970 to 1983 sterility treatment was broken off by 218 patients of the women's clinic, Wilhelm-Pieck-University Rostock. From 103 returned questionnaires 194 individual responses were recorded suggesting that on the average more than one reason led to the decision to break off treatment. Personal problems such as unsuccessful treatment, advanced age, too high demand on time, conflicts in marriage, consumption of stimulants, and diseases (61.2%) were prevalent. Pregnancy (50.5%), adoption (20.4%), occupational problems (13.6%), and a problematic physician-patient-relationship (6.8%) were also cited. Already from the beginning of treatment these patients were not willing to cooperate, to supply necessary information and fully participate. A tendency towards a shifting of the problems could be observed. 24.3% of the patients continued seeing a gynaecologist. 15.5% asked for recommencement of sterility treatment.