Second Data Release from the European Pulsar Timing Array: Challenging the Ultralight Dark Matter Paradigm

Pulsar Timing Array experiments probe the presence of possible scalar or pseudoscalar ultralight dark matter particles through decade-long timing of an ensemble of galactic millisecond radio pulsars. With the second data release of the European Pulsar Timing Array, we focus on the most robust scenario, in which dark matter interacts only gravitationally with ordinary baryonic matter. Our results show that ultralight particles with masses 10^{-24.0}  eV≲m≲10^{-23.3}  eV cannot constitute 100% of the measured local dark matter density, but can have at most local density ρ≲0.3  GeV/cm^{3}.

Limits on Anisotropy in the Nanohertz Stochastic Gravitational Wave Background

The paucity of observed supermassive black hole binaries (SMBHBs) may imply that the gravitational wave background (GWB) from this population is anisotropic, rendering existing analyses suboptimal. We present the first constraints on the angular distribution of a nanohertz stochastic GWB from circular, inspiral-driven SMBHBs using the 2015 European Pulsar Timing Array data. Our analysis of the GWB in the ~2-90 nHz band shows consistency with isotropy, with the strain amplitude in l>0 spherical harmonic multipoles ≲40% of the monopole value. We expect that these more general techniques will become standard tools to probe the angular distribution of source populations.

Evidence for the role of follicle stimulating hormone in maintaining the oocyte meiotic arrest in pre-antral follicles

The study was designed to clarify the physiological role of FSH in maintaining the meiotic arrest in vitro of oocytes derived from intact and from hypophysectomized hamsters. The sensitivity to FSH in maintaining the meiotic arrest of oocytes during incubation of pre-antral follicles of adult golden hamsters was estimated: log dose-response curves were characterized by an ED50 of about 0.2 pg FSH/ml (= 1 microU). After hypophysectomy oocytes of the pre-antral follicles were screened for the presence of a germinal vesicle (GV). The breakdown of the GV (GVBD) rose from 0 on day 0 to 48.8 +/- 13.8% on day 1, to 55.9 +/- 6.8% on day 2 and to 64.3 +/- 7.4 on day 6 (p < 0.001 vs day 0). Incubation without FSH of the pre-antral follicles obtained from the same hypophysectomized animals showed an almost complete disappearance of the GV at the same time intervals. Incubation with 2 pg FSH/ml (= 10 microU) still demonstrated the inhibiting effect of FSH on the meiotic resumption: 13.4 +/- 4.3% (day 0), 36.9 +/- 16.3% (day 1), 38.7 +/- 21.0% (day 2) and of 38.1 +/- 12.6% (p > 0.1) on day 6. These results demonstrate that very low doses of FSH are able to maintain the meiotic arrest in oocytes of pre-antral follicles of the golden hamster and that deprivation of FSH by hypophysectomy involves a disappearance of GV oocytes to a certain extent.

Different effects of anesthetics on spontaneous leukocyte rolling in rat skin

In immunological reactions, leukocytes need to travel from the intravascular space through the vessel wall into the surrounding tissue. The first step in this process is leukocyte rolling, which has often been studied in anesthetized animals. In this study, we investigated the effect of pentobarbital, Hypnorm and both components of the latter, fentanyl and fluanisone, on this primary leukocyte-endothelial cell interaction. Using intravital brightfield video microscopy, observations were made in postcapillary venules in the intact skin of the nailfold of trained conscious Lewis rats. Subsequently, the animals were anesthetized and observations were made in vivo. Leukocyte rolling was significantly elevated after injection of Hypnorm or fentanyl, while pentobarbital and fluanisone had no effect. None of the anesthetics affected leukocyte rolling velocity. Blood flow was significantly increased only after injection of Hypnorm and fluanisone. No correlation existed between the relative changes in leukocyte rolling and concomitant changes in blood flow. The results show that the level of leukocyte rolling can be affected by anesthetics. These changes are probably not mediated by changes in local hemodynamics. Pentobarbital anesthesia does not influence leukocyte rolling. Therefore, pentobarbital is a suitable anesthetic for observation of leukocyte rolling in skin. Hypnorm significantly increases the level of rolling in skin venules. This effect seems to be caused mainly by fentanyl.

Posttraumatic aneurysm of the right atrium

We report on an acquired right atrial false aneurysm, which was removed under extracorporeal circulation. The patient remembered three occasions of blunt chest trauma with rib fractures. Clinical symptoms were ongoing dyspnea, chest pain, and atrial fibrillation.

Spontaneous leukocyte rolling in venules in untraumatized skin of conscious and anesthetized animals

Intravital bright-field videomicroscopy was used to investigate whether leukocyte rolling can be observed under normal physiological conditions. We studied skin venules in trained conscious rats and anesthetized rats and mice without touching the skin itself. Leukocyte rolling was spontaneously present in all hindpaw venules of Lewis rats (diam 8-27 microns) and also in all mouse ear venules (Swiss, 13-38 microns; BALB/c, 12-56 microns). Rolling levels (in leukocytes/min, median and range) were 8 (3-15) in conscious rats, 9 (3-19) in anesthetized rats, 30 (5-160) in anesthetized Swiss mice, and 10 (3-22) in anesthetized BALB/c mice. These levels appeared to be independent of time. Noninvasive mechanical stimulation induced an average increase of 32%. Fluorescent labeling of leukocytes in vivo with acridine orange had no influence. In Swiss mice, the rolling velocity was < 50 microns/s for > 75% of the leukocytes (median 31 microns/s); this parameter did not correlate with reduced velocity (17-68 s-1) and hence wall shear rate. Our finding that leukocyte rolling is spontaneously present in skin venules of anesthetized and conscious animals suggests a constant vigilance of the host defense mechanisms in the skin.

Comparison of heparan sulfate proteoglycans from equine and human glomerular basement membranes

1. Proteoglycans extracted from human and equine glomerular basement membranes (GBM) were purified by ion-exchange chromatography and gel filtration. 2. The glycoconjugates had an apparent molecular mass of 200-400 kDa and consisted of 75% protein and 25% glycosaminoglycan. Glycosidase and HNO2 treatment and the amino sugar and sulfate composition of both proteoglycan preparations identified heparan sulfate (HS) as the predominant saccharide chain. 3. Hydrolysis with trifluoromethanesulfonic acid yielded comparable core proteins with molecular masses of ca 160 and 120 kDa. 4. The HS chains had an apparent molecular mass of 18 kDa. Results of heparitinase digestion and HNO2-treatment indicated a clustering of sulfate groups in the distal part of the HS side chains. 5. Peptide mapping after trypsin, clostripain or V8 protease digestion of radiolabeled human and equine heparan sulfate proteoglycans (HSPG) preparations with three different separation techniques showed large differences. 6. Polyclonal antisera raised against the HSPGs reacted against the core proteins. Both HSPG preparations and their antisera showed ca 40% cross-reactivity. About 50% of monoclonal antisera elicited against one HSPG preparation showed reaction with both HSPG preparations. 7. Polyclonal antisera stained all basement membranes in an intense linear fashion in indirect immunofluorescence studies of kidney sections from horse, man and various mammalian species. 8. Biochemical and immunological data indicate that HSPGs from equine and human GBM have a comparable structure, but the core proteins differ considerably.