Florian Frommlet

Platelets are mitogenic for periosteum-derived cells

The early stages of bone regeneration are associated with a high mitogenic activity of periosteal cells. Here we addressed the question of whether platelets that accumulate within the developing haematoma can account for this tissue response. Addition of platelets, platelet‐released supernatants, platelet membranes, and microparticles to bovine periosteum‐derived cells resulted in an increase in 3H‐thymidine incorporation; lipid extracts had no effect. Platelet‐released supernatants retained their activity after incubation at 56°C, but not at 100°C. Gel chromatographic analysis revealed the highest mitogenic activity at approximately 35 kD. Of the factors released from activated platelets, basic fibroblast growth factor (bFGF) and platelet‐derived growth factor (PDGF) increased 3H‐thymidine incorporation. The mitogenic activity of platelet‐released supernatants was decreased by anti‐PDGF, and anti‐bFGF antibodies. Platelet‐released supernatants increased the number of proliferating periosteum‐derived cells as determined by the expression pattern of Ki67. Platelet‐released supernatants also resulted in a stimulation of cell proliferation in periosteal explants. These results suggest that platelets have the potential to stimulate the mitogenic response of the periosteum during bone repair.

Fokker–Planck Equations as Scaling Limits of Reversible Quantum Systems

We consider a quantum particle moving in a harmonic exterior potential and linearly coupled to a heat bath of quantum oscillators. Caldeira and Leggett derived the Fokker–Planck equation with friction for the Wigner distribution of the particle in the large-temperature limit; however, their (nonrigorous) derivation was not free of criticism, especially since the limiting equation is not of Lindblad form. In this paper we recover the correct form of their result in a rigorous way. We also point out that the source of the diffusion is physically restrictive under this scaling. We investigate the model at a fixed temperature and in the large-time limit, where the origin of the diffusion is a cumulative effect of many resonant collisions. We obtain a heat equation with a friction term for the radial process in phase space and we prove the Einstein relation in this case.

Motility-related protein-1/CD9 expression in head and neck squamous cell carcinoma

Motility‐related protein (MRP)‐1/CD9 is implicated in cell adhesion and motility and was shown to be clearly involved in tumor prognosis and angiogenesis. Elevated MRP‐1/CD9 expression on tumor cells has been linked to a favorable prognosis in breast cancer, colon cancer, lung cancer, and HNSCC. Because MRP‐1/CD9 is associated with angiogenesis, it might play a role in tumor angiogenesis as well.

The end of submacular surgery for age-related macular degeneration? A meta-analysis

BackgroundThe aim of this meta-analysis was to summarize and to discuss the results of the four main submacular surgical procedures for age-related macular degeneration (AMD) as reported in the literature through 2004 and to compare them to the Submacular Surgery Trials (SST) data.Methods The existing data in the literature on submacular surgery for AMD from 1992 to 2004 were evaluated. The main outcomes were proportion of patients with two or more lines of improvement in visual acuity (VA) and proportion with two or more lines of deterioration in VA after surgery.Results Eighty-eight studies including 1,915 cases met the inclusion criteria. Estimates for the treatment outcome within the four groups of treatment based on a logistic regression model gave comparable results for removal of choroidal neovascularization (CNV) (improvement of VA 28%, deterioration of VA 25%), macular translocation (improvement of VA 31%, deteriora-tion of VA 27%), and for transplantation of pigment epithelium (improvement of VA 22%, deterioration of VA 21%). Estimates for removal of subretinal hemorrhage were significantly different (improvement of VA 62%, deterioration of VA 13%).Conclusions Selected case series showed superior results of VA compared to the SST. The question of whether this is due to selection bias that seems inevitable when dealing with medium-sized nonrandomized case series or due to better results in single centers cannot be answered. In our opinion there still seem to be indications for submacular surgery such as in patients with AMD with low preoperative VA due to large hemorrhagic or fibrotic membranes or nonresponders to photodynamic therapy (PDT).

The prevalence of hypertension, obesity and dyslipidemia in individuals of over 30 years of age belonging to minorities from the pasture area of Xinjiang

BackgroundThe prevalence of population-wide hypertension, obesity and dyslipidemia has not been well studied in the pasture area of Xinjiang. The present epidemiological study was performed to determine the prevalence of hypertension, obesity and dyslipidemia in minority populations from the pasture area of Xinjiang and to discuss the potential risk factors for hypertension.MethodsA population-based, cross-sectional study in the Xinjiang pasture area was performed which included 2251 participants aged over 30 years (90.33% participation rate) of whom 71.26% were Kazaks. Several risk factors were considered: hypertension (defined as systolic or diastolic blood pressure or both of at least 140/90 mmHg measured on one occasion or treatment for hypertension) overweight/obesity (body mass index ≥ 25 kg/m2) alcohol intake, smoking/tobacco use and dyslipidemia. Outcomes were prevalence of hypertension, obesity and dyslipidemia and the associated risk factors of hypertension detected by multivariate logistic regression analysis taking into account various metabolic and lifestyle characteristics.ResultsThe prevalence of hypertension, overweight/obesity and dyslipidemia in all participants from the pasture area of Xinjiang was 51.9%, 47.9% and 49.2% respectively. Independently, the prevalence and awareness of hypertension was 52.6% and 15.3% among Kazaks (n = 1604), 54.6% and 14.1% among Uygurs (n = 418), 39.5% and 16.1% among Mongolians (n = 81) and 43.9% and 18.2% among non-Xinjiang-born Han immigrants (n = 148). The prevalence of overweight/obesity in Kazaks, Uygurs, Mongolians and Han immigrants was 46.7%, 48.9%, 62.5% and 50.3%, respectively. The prevalence of dyslipidemia in the four ethnic groups mentioned was 53.5%, 34.8%, 49.3% and 47.3%, respectively. The mean blood pressure in all participants was 136/86 mmHg (pre-hypertensive), the mean BMI was 24.7 kg/m2. Based on multiple logistic regression analysis, the significant risk factors for hypertension were age [1.07(1.06-1.09), P < 0.0001], overweight/obesity [overweight: 1.61(1.22-2.13), p = 0.0007; obesity: 1.95 (1.33-2.87), p = 0.0007], hypercholesterolemia [1.30(1.15-1.47), p < 0.0001] and an alcohol intake of over 30 g/day [2.22(1.43-3.45), p = 0.0004].ConclusionsThe considerably high prevalence of hypertension, overweight/obesity and dyslipidemia among the minority population aged over 30 from the pasture area of Xinjiang calls for effective preventive measures. Age, increased body mass index, hypercholesterolemia and ≥30 g/d alcohol intake can be counted as risk factors for hypertension, but further genetic or environmental clarification would be desirable to explain the unusually high prevalence of the conditions mentioned above.

Risk-Adjusted Outcome Measurement in Pediatric Allogeneic Stem Cell Transplantation

The purpose of the study was to define a risk score for 1-year treatment-related mortality (TRM) in children undergoing allogeneic stem cell transplantation as a basis for risk-adjusted outcome assessment. We analyzed 1364 consecutive stem cell transplants performed in 24 German and Austrian centers between 1998 and 2003. Five well-established risk factors were tested by multivariate logistic regression for predictive power: patient age, disease status, donor other than matched sibling donor, T cell depletion (TCD), and preceding stem cell transplantation. The risk score was defined by rounding the parameter estimates of the significant risk factors to the nearest integer. Crossvalidation was performed on the basis of 5 randomly extracted equal-sized parts from the database. Additionally, the score was validated for different disease entities and for single centers. Multivariate analysis revealed a significant correlation of TRM with 3 risk factors: age >10 years, advanced disease, and alternative donor. The parameter estimates were 0.76 for age, 0.73 for disease status, and 0.97 for donor type. Rounding the estimates resulted in a score with 1 point for each risk factor. One-year TRM (overall survival [OS]) were 5% (89%) with a score of 0, 18% (74%) with 1, 28% (54%) with 2, and 53% (27%) with 3 points. Crossvalidation showed stable results with a good correlation between predicted and observed mortality but moderate discrimination. The score seems to be a simple instrument to estimate the expected mortality for each risk group and for each center. Measuring TRM risk-adjusted and the comparison between expected and observed mortality may be an additional tool for outcome assessment in pediatric stem cell transplantation.

Copositivity cuts for improving SDP bounds on the clique number

Adding cuts based on copositive matrices, we propose to improve Lovász’ bound θ on the clique number and its tightening θ′ introduced by McEliece, Rodemich, Rumsey, and Schrijver. Candidates for cheap and efficient copositivity cuts of this type are obtained from graphs with known clique number. The cost of previously established semidefinite programming bound hierarchies starting with θ′ rapidly increases with the order (and quality requirements). By contrast, the bounds proposed here are relatively cheap in the sense that computational effort is comparable to that required for θ′.

Biological variation, individuality and critical differences of eight biochemical blood constituents in budgerigars (Melopsittacus undulatus)

The aim of the study was to obtain basic data on individual biological variation, the required number of specimens to define the homeostatic setpoint (the aspired value of a variable adjusted to the individuals homeostasis) and critical differences of selected chemistry parameters in budgerigars (Melopsittacus undulatus). Blood from 99 healthy budgerigars was sampled 12 times at four-week intervals. Aspartate aminotransferase (ast), calcium, creatine kinase (ck), glutamate dehydrogenase (gldh), glucose, lactate dehydrogenase (ldh), total protein and uric acid were investigated. The indices of individuality obtained in the present study were relatively low (total protein 0·93, ast 1·02, gldh 1·04, ck 1·12, ldh 1·24, uric acid 1·26, glucose 1·39, calcium 1·61) and suggest that population-based reference limits might be useful. Comparison of data showed that the application of intraindividual reference values identified much greater variation in the reference values than using conventional population-based reference limits. Otherwise, the moderate to low degrees of individuality may allow the use of reference values of one individual as a standard for another individual of the same species. The critical differences that define the change needed between two serial results to indicate a biological change was highest in gldh with 120 per cent or 1·7 U/l. In calcium, a change of 30·5 per cent or 0·5 mmol/l would be significant. In the other parameters critical differences varied between 38 per cent in glucose, up to 93 per cent in uric acid.

Improved SDP bounds for minimizing quadratic functions over the \(\ell^{1}\)-ball

AbstractNesterov suggested an SDP-based bound for the problem to minimize a quadratic form over then