pH-Abhängigkeit der Cytochrom c2 (c)-Reduktion und des Membranpotentials (Δ Ψ) in Modellsystemen und Chromatophoren von Purpurbakterien

Ubiquinol-1 reduces cytochrome c in solution at a rate which increases 10-fold with an increase in pH by one unit within the range of 6.5 – 8.5. Light-dependent generation of ΔΦ in proteoliposomes containing Rhodospirillum rubrum reaction centers in the presence of ubiquinone-1 and cytochrome c is also stimulated with an increase in pH from 6.5 to 8.5. The ΔΦ generation in R. rubrum and Rhodobacter sphaeroides is described by a bell-shaped pH-dependence curve, the maximum responses being observed at pH 7.5–8.0. The dependence is retained with antimycin A (but not myxothiazol). The magnitude of the residual ΔΦ generation in the presence of myxothiazol or its combination with antimycin remains relatively constant in the pH range 6.5 to 9.5. Switching off the light, cytochrome c₂ is reduced in Rb. sphaeroides chromatophores, with the maximum rate at pH 7.3 – 7.6. The data obtained suggest that cytochrome c₂ reduction by ubiquinol in purple bacteria is accomplished by cytochrome bc₁ complex. In proteoliposomes and soluble systems, this process depends on a direct nonenzymatic reaction.     

Estimation of the cardiac output in the presence of a pathological arteriovenous shunt

The aim of the investigation was to develop a quantitative method of determining the cardiac output by the thermodilution principle in patients with congenital heart diseases accompanied by a pathological arteriovenous shunt. A method of graphic analysis of the curves based on standard ratios between heights of the descending part is suggested. Values of left-right shunts similar to results obtained by the Fick method can be obtained by the method now suggested.M. F. Vladimirskii Moscow Regional Clinical Research Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 239–240, February, 1980.     

14-3-3 proteins as potential oncogenes

14-3-3 proteins are a family of highly conserved cellular proteins that play key roles in the regulation of central physiological pathways. More than 200 14-3-3 target proteins have been identified, including proteins involved in mitogenic and cell survival signaling, cell cycle control and apoptotic cell death. Importantly, the involvement of 14-3-3 proteins in the regulation of various oncogenes and tumor suppressor genes points to a potential role in human cancer. The present review summarizes current findings implicating a 14-3-3 role in cancer while discussing potential mechanisms and points of action of 14-3-3 during cancer development and progression.     

Repression of cap-dependent translation attenuates the transformed phenotype in non-small cell lung cancer both in vitro and in vivo

Aberrant hyperactivation of the cap-dependent protein synthesis apparatus has been documented in a wide range of solid tumors, including epithelial carcinomas, but causal linkage has only been established in breast carcinoma. In this report, we sought to determine if targeted disruption of deregulated cap-dependent translation abrogates tumorigenicity and enhances cell death in non-small cell lung cancer (NSCLC). NSCLC cell lines were stably transfected with either wild-type 4E-BP1 (HA-4E-BP1) or the dominant-active mutant 4E-BP1(A37/A46) (HA-TTAA). Transfected NSCLC cells with enhanced translational repression showed pronounced cell death following treatment with gemcitabine. In addition, transfected HA-TTAA and HA-4E-BP1wt proteins suppressed growth in a cloning efficiency assay. NSCLC cells transduced with HA-TTAA also show decreased tumorigenicity in xenograft models. Xenograft tumors expressing HA-TTAA were significantly smaller than control tumors. This work shows that hyperactivation of the translational machinery is necessary for maintenance of the malignant phenotype in NSCLC, identifies the molecular strategy used to activate translation, and supports the development of lung cancer therapies that directly target the cap-dependent translation initiation complex.     

A randomized, controlled, prospective study validating the acquisition of percutaneous renal collecting system access skills using a computer based hybrid virtual reality surgical simulator: phase I

PURPOSE: The need to develop new methods of surgical training combined with advances in computing has led to the development of sophisticated virtual reality surgical simulators. The PERC Mentortrade mark is designed to train the user in percutaneous renal collecting system access puncture. We evaluated and established face, content and construct validation of the simulator in this task. MATERIALS AND METHODS: A total of 63 trainees underwent baseline testing on the simulator, consisting of percutaneous renal puncture followed by the introduction of a guidewire into the collecting system. Subjects were then randomized to an intervention arm, in which they underwent 2, 30-minute training sessions on the simulator, and a control arm, in which no further training was given, followed by repeat testing. Performance was assessed using a global rating scale and by virtual reality derived parameters. RESULTS: There were no significant differences between the 2 groups with respect to baseline measures. Subjects who underwent training with the simulator demonstrated significant improvement in objective and subjective parameters compared to their baseline performance and compared to the untrained control group. Spearman rank correlations demonstrated a significant relationship between multiple parameters of the objective and subjective data. CONCLUSIONS: Training on the simulator improves virtual reality skills. It may allow trainees to develop the basic skills necessary to perform percutaneous renal collecting system access. Face and content validity were demonstrated and construct validity was supported by establishing convergent validity.     

Results of a Survey of Neurosurgical Practice Patterns Regarding the Prophylactic use of Anti-Epilepsy Drugs in Patients with Brain Tumors

Summary Introduction: The American Association of Neurology issued guidelines discouraging the prophylactic use of anti-epilepsy drugs (AEDs) in patients with brain tumors. We surveyed neurosurgeons to evaluate practice patterns with regard to using AEDs in neurosurgical patients with brain tumors. Methods: The survey consisted of 18 questions. Two group email blasts containing an internet link to the survey were sent to members of the American Association of Neurological Surgeons with email addresses. Uni- and multi-variate analysis of the responses was performed using t-test, Fisher’s exact test, or chi-squared test, where appropriate. Results: The response rate was 15.5% (386/2491). The majority of respondents (270/386; 70.0%) had more than 5 years of experience in neurosurgery. Most respondents described their practices as general (224/379; 59.1%); about one-third were members of the Joint Section on Tumors (136/381; 35.7%). More than 70% of respondents reported routine use of AED prophylaxis for patients with intra-axial gliomas or brain metastases. AED prophylaxis was also routinely used for extra-axial benign tumors or stereotactic biopsies by 53.8% and 21.4%, respectively. On multivariate analysis, the number of years in practice of ABNS certified neurosurgeons was the strongest predictor for the use of AED prophylaxis. Conclusions: Routine use of AED prophylaxis in patients with brain tumors undergoing neurosurgical procedures remains the prevailing practice pattern among members of the AANS. Additional larger prospective studies with appropriate patient stratification culminating in development of neurosurgical guidelines on AED prophylaxis in brain tumor patients is warranted.     

The osteoinductive potential of printable, cell-laden hydrogel-ceramic composites

Hydrogels used as injectables or in organ printing often lack the appropriate stimuli to direct osteogenic differentiation of embedded multipotent stromal cells (MSCs), resulting in limited bone formation in these matrices. Addition of calcium phosphate (CaP) particles to the printing mixture is hypothesized to overcome this drawback. In this study we have investigated the effect of CaP particles on the osteoinductive potential of cell-laden hydrogel-CaP composite matrices. To this end, apatitic nanoparticles have been included in Matrigel constructs where after the viability of embedded progenitor cells was assessed in vitro. In addition, the osteoinductive potential of cell-laden Matrigel containing apatitic nanoparticles was investigated in vivo and compared with composites containing osteoinductive biphasic calcium phosphate (BCP) microparticles after subcutaneous implantation in immunodeficient mice. Histological and immunohistochemical analysis of the tissue response as well as in vivo bone formation revealed that apatitic nanoparticles were osteoinductive and induced osteoclast activation, but without bone formation. The BCP particles were more effective in inducing elaborate bone formation at the ectopic location.     

Does preoperative symptom classification impact prognosis in patients with clinically localized upper-tract urothelial carcinoma managed by radical nephroureterectomy?

ObjectivesTo evaluate if preoperative symptom classification could refine prediction of outcomes for patients with clinically localized upper-tract urothelial carcinoma (UTUC) managed by radical nephroureterectomy (RNU).MethodsData on 654 patients with localized UTUC who underwent RNU were reviewed. Preoperative symptoms were classified as incidental (S1), local (S2), and systemic (S3). Clinical and pathologic data were compared between the cohorts. Kaplan-Meier analyses and Cox proportional hazard modeling were used to determine recurrence-free and cancer-specific survival amongst the symptom cohorts.ResultsSymptom classification was S1 in 213 (33%) patients, S2 in 402 (61%), and S3 in 39 (6%). S3 symptoms were associated with advanced pathology, including higher stage, grade, and lymph node (LN) positivity. Five and 10-year recurrence-free and cancer-specific survival estimates were similar for patients with S1 and S2 symptoms (P = 0.75 and 0.58, respectively), but was worse for patients with S3 symptoms (P < 0.001 for both). On multivariate analysis adjusting for final pathologic stage, grade, and LN status, S3 symptoms were not an independent predictor of recurrence (HR 1.44, P = 0.19) or death due to disease (HR 1.66, P = 0.07). Addition of symptom classification, however, increased the accuracy of a model consisting of stage, grade, and LNs for prediction of recurrence-free and cancer-specific survival by 1.4% and 1.3%, respectively (P < 0.001 for both).ConclusionsLocal symptoms do not confer worse prognosis compared with patients with incidentally detected UTUC. However, systemic symptoms are associated with worse outcomes despite apparently effective RNU. Patients with systemic symptoms may harbor micrometastatic disease and could potentially benefit from a more rigorous metastatic evaluation or perioperative chemotherapy regimens.