Reactivation of the mitosis-promoting factor in postmitotic cardiomyocytes

Cardiomyocytes cease to divide shortly after birth and an irreversible cell cycle arrest is evident accompanied by the downregulation of cyclin-dependent kinase activities. To get a better understanding of the cardiac cell cycle and its regulation, the effect of functional recovery of the mitosis-promoting factor (MPF) consisting of cyclin B1 and the cyclin-dependent kinase Cdc2 was assessed in primary cultures of postmitotic ventricular adult rat cardiomyocytes ( ARC). Gene transfer into ARC was achieved using the adenovirus-enhanced transferrinfection system that was characterized by the absence of cytotoxic events. Simultaneous ectopic expression of wild-type versions of cyclin B1 and Cdc2 was sufficient to induce MPF activity. Reestablished MPF resulted in a mitotic phenotype, marked by an abnormal condensation of the nuclei, histone H3 phosphorylation and variable degree of decay of the contractile apparatus. Although a complete cell division was not observed, the results provided conclusive evidence that cell cycle-related events in postmitotic cardiomyocytes could be triggered by genetic intervention downstream of the G1/S checkpoint. This will be of importance to design novel strategies to overcome the proliferation arrest in adult cardiomyocytes

Two-photon interference with two independent pseudo-thermal sources

The nature of two-photon interference is a subject that has aroused renewed interest in recent years and is still under debate. In this paper we report the first observation of two-photon interference with independent pseudo-thermal sources in which sub-wavelength interference is observed. The phenomenon may be described in terms of the classical statistical distribution of the two sources and their optical transfer functions.Comment: Phys. Rev. A 74, 053807 (2006

Density functional theory in one-dimension for contact-interacting fermions

A density functional theory is developed for fermions in one dimension, interacting via a delta-function. Such systems provide a natural testing ground for questions of principle, as the local density approximation should work well for short-ranged interactions. The exact-exchange contribution to the total energy is a local functional of the density. A local density approximation for correlation is obtained using perturbation theory and Bethe-Ansatz results for the one-dimensional contact-interacting uniform Fermi gas. The ground-state energies are calculated for two finite systems, the analogs of Helium and of Hooke's atom. The local approximation is shown to be excellent, as expected.Comment: 10 pages, 7 Figure

Physical Controls on Carbonate Intraclasts: Modern Flat Pebbles From Great Salt Lake, Utah

In carbonate‐forming environments, authigenic minerals can cement surface sediments into centimeter‐sized intraclasts that are later reworked into “flat‐pebble” or “edgewise” conglomerates. Flat‐pebble conglomerates comprise only a small portion of facies in modern marine environments but are common in ancient strata, implying that seafloor cements were more widespread in the past. Flat‐pebble conglomerates nearly disappeared after the Ordovician radiation, yet it is unclear if this decline was due to changing seawater chemistry or if increased infaunalization and bioturbation simply worked to break down nascent clasts. We discovered a process analog that produces flat‐pebble conglomerates around the Great Salt Lake, Utah, USA, and studied these facies using field observations, wave models, satellite imagery, petrography, and microanalytic chemical data. Clasts were sourced from wave‐rippled grainstone that cemented in situ in offshore environments. Lake floor cements formed under aragonite saturation states that are lower than modern marine settings, suggesting that physical processes are at least as important as chemical ones. Results from our wave models showed that coarse sediments near the field site experience quiescent periods of up to 6 months between suspension events, allowing isopachous cements to form. Using a simple mathematical framework, we show that the main difference between Great Salt Lake and modern, low‐energy marine settings is that the latter has enough bioturbating organisms to break up clasts. Observations from Great Salt Lake demonstrate how geologic trends in flat‐pebble abundance could largely reflect changes in total infaunal biomass and ecology without requiring regional‐to‐global changes in seawater chemistry

Physical Controls on Carbonate Intraclasts: Modern Flat Pebbles From Great Salt Lake, Utah

In carbonate‐forming environments, authigenic minerals can cement surface sediments into centimeter‐sized intraclasts that are later reworked into “flat‐pebble” or “edgewise” conglomerates. Flat‐pebble conglomerates comprise only a small portion of facies in modern marine environments but are common in ancient strata, implying that seafloor cements were more widespread in the past. Flat‐pebble conglomerates nearly disappeared after the Ordovician radiation, yet it is unclear if this decline was due to changing seawater chemistry or if increased infaunalization and bioturbation simply worked to break down nascent clasts. We discovered a process analog that produces flat‐pebble conglomerates around the Great Salt Lake, Utah, USA, and studied these facies using field observations, wave models, satellite imagery, petrography, and microanalytic chemical data. Clasts were sourced from wave‐rippled grainstone that cemented in situ in offshore environments. Lake floor cements formed under aragonite saturation states that are lower than modern marine settings, suggesting that physical processes are at least as important as chemical ones. Results from our wave models showed that coarse sediments near the field site experience quiescent periods of up to 6 months between suspension events, allowing isopachous cements to form. Using a simple mathematical framework, we show that the main difference between Great Salt Lake and modern, low‐energy marine settings is that the latter has enough bioturbating organisms to break up clasts. Observations from Great Salt Lake demonstrate how geologic trends in flat‐pebble abundance could largely reflect changes in total infaunal biomass and ecology without requiring regional‐to‐global changes in seawater chemistry

A 2-year prospective study of patient-relevant outcomes in patients operated on for knee osteoarthritis with tibial osteotomy

BACKGROUND: Tibial osteotomy is a treatment for younger and/or physically active patients suffering from uni-compartmental knee osteoarthritis. The open wedge osteotomy by the hemicallotasis technique includes the use of external fixation. The use of external fixation has several advantages, as early mobilization and the opportunity for optimal correction. However, the hemicallotasis technique has also been described as a cumbersome procedure for the patient. The aim of this study was to prospectively evaluate patient-relevant outcomes during the first 2 post-operative years. Especially the treatment period, during which external fixation was used, was closely monitored. METHODS: In an uncontrolled study, fifty-eight consecutive patients, 30 men and 28 women (mean age 54 years) were operated on by the hemicallotasis technique were evaluated with the patient-relevant outcome measure Knee injury and Osteoarthritis Outcome Score (KOOS) preoperatively, during the treatment with external fixation, one week after removal of the external fixation, at 6 months, and at one and two years postoperatively. RESULTS: At the 2-year postoperative follow-up, all subscales of the KOOS were improved (p < 0.001), mostly in pain (41–80 on a 0–100 worst to best scale) and knee-related quality of life (21–61 on a 0–100 worst to best scale), compared to the preoperative status. Significant improvements in pain and other symptoms, function of daily life and quality of life were seen already during the treatment period (mean 98 ± 18 days) with the external fixation. More demanding functions such as kneeling, squatting, jumping and running, were improved first after extraction of the external fixation device and the pins. CONCLUSION: Tibial osteotomy by the hemicallotasis technique yields large improvement in self-rated pain, function and quality of life, which persists over two years. Surprisingly, large improvements occurred already during the immediate post-operative period when the external fixation was still used