Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433

SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.

Search for Dark Matter Annihilation Signals in the H.E.S.S. Inner Galaxy Survey

The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented γ-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (≳100  GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant γ-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section ⟨σv⟩. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach ⟨σv⟩ values of 3.7×10^{-26}  cm^{3} s^{-1} for 1.5 TeV DM mass in the W^{+}W^{-} annihilation channel, and 1.2×10^{-26}  cm^{3} s^{-1} for 0.7 TeV DM mass in the τ^{+}τ^{-} annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based γ-ray observations thus probe ⟨σv⟩ values expected from thermal-relic annihilating TeV DM particles.

Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE, [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to a month after its 2021 outburst, observed using the High Energy Stereoscopic System. The VHE emission has a similar temporal profile to lower-energy GeV emission, indicating a common origin, with a two-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic-rays to very high energies.

Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera-electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

Towards high-energy, high-resolution computed tomography via a laser driven micro-spot gamma-ray source

Computed Tomography (CT) is a powerful method for non-destructive testing (NDT) and metrology awakes with expanding application fields. To improve the spatial resolution of high energy CT, a micro-spot gamma-ray source based on bremsstrahlung from a laser wakefield accelerator was developed. A high energy CT using the source was performed, which shows that the resolution of reconstruction can reach 100 μm at 10% contrast. Our proof-of-principle demonstration indicates that laser driven micro-spot gamma-ray sources provide a prospective way to increase the spatial resolution and toward to high energy micro CT. Due to the advantage in spatial resolution, laser based high energy CT represents a large potential for many NDT applications.

Experimental Evidence of Kinetic Effects in Indirect-Drive Inertial Confinement Fusion Hohlraums

We present the first experimental evidence supported by simulations of kinetic effects launched in the interpenetration layer between the laser-driven hohlraum plasma bubbles and the corona plasma of the compressed pellet at the Shenguang-III prototype laser facility. Solid plastic capsules were coated with carbon-deuterium layers; as the implosion neutron yield is quenched, DD fusion yield from the corona plasma provides a direct measure of the kinetic effects inside the hohlraum. An anomalous large energy spread of the DD neutron signal (∼282  keV) and anomalous scaling of the neutron yield with the thickness of the carbon-deuterium layers cannot be explained by the hydrodynamic mechanisms. Instead, these results can be attributed to kinetic shocks that arise in the hohlraum-wall-ablator interpenetration region, which result in efficient acceleration of the deuterons (∼28.8  J, 0.45% of the total input laser energy). These studies provide novel insight into the interactions and dynamics of a vacuum hohlraum and near-vacuum hohlraum.

Alleviation of doxorubicin–induced hepatorenal toxicities with sesamin via the suppression of oxidative stress

Hepatorenal toxicities are an important side effect of anthracycline antibiotics. The objective of this study was to determine whether sesamin (Ses) protects against acute doxorubicin (DOX)-induced hepatorenal toxicities. Rats received daily treatment with either 0.5% carboxymethylcellulose (10 mL/kg) or Ses (10, 20 and 40 mg/kg) orally for 10 days, followed by an intravenous injection at day 8 of either saline (10 mL/kg) or DOX (20 mg/kg). Hepatorenal toxicity was assessed by measuring the levels of serum creatinine (Cre), blood urea nitrogen (BUN), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). The protein expression of 4-hydroxynonenal (4-HNE) in hepatorenal tissues was evaluated using immunohistochemistry. The malondialdehyde (MDA) content and antioxidant activity in the kidney and liver tissues were also measured. The results suggest that pretreatment with Ses ameliorated DOX-induced liver and kidney injury by lowering the serum ALT, AST, ALP, Cre and BUN levels ( p < 0.05 or p < 0.01), and the histological damage to the liver and kidney tissues induced by DOX compared to control were also significantly attenuated by Ses. Furthermore, Ses significantly decreased the DOX-induced increase of MDA and 4-HNE and increased the activity of CAT, SOD and GPX compared to the DOX-treated rats ( p < 0.05 or p < 0.01), whereas the change of DOX + Ses (10 mg/kg) group is not significant compared to the DOX-treated group ( p > 0.05). These findings indicate that Ses elicits a typical protective effect against DOX-induced acute hepatorenal toxicity via the suppression of oxidative stress.

A comparison of the clinical characteristics of women with recurrent major depression with and without suicidal symptomatology

BACKGROUND

The relationship between recurrent major depression (MD) in women and suicidality is complex. We investigated the extent to which patients who suffered with various forms of suicidal symptomatology can be distinguished from those subjects without such symptoms.

METHOD

We examined the clinical features of the worst episode in 1970 Han Chinese women with recurrent DSM-IV MD between the ages of 30 and 60 years from across China. Student's t tests, and logistic and multiple logistic regression models were used to determine the association between suicidality and other clinical features of MD.

RESULTS

Suicidal symptomatology is significantly associated with a more severe form of MD, as indexed by both the number of episodes and number of MD symptoms. Patients reporting suicidal thoughts, plans or attempts experienced a significantly greater number of stressful life events. The depressive symptom most strongly associated with lifetime suicide attempt was feelings of worthlessness (odds ratio 4.25, 95% confidence interval 2.9-6.3). Excessive guilt, diminished concentration and impaired decision-making were also significantly associated with a suicide attempt.

CONCLUSIONS

This study contributes to the existing literature on risk factors for suicidal symptomatology in depressed women. Identifying specific depressive symptoms and co-morbid psychiatric disorders may help improve the clinical assessment of suicide risk in depressed patients. These findings could be helpful in identifying those who need more intense treatment strategies in order to prevent suicide.

Association of AFLP and SCAR markers with common leafspot resistance in autotetraploid alfalfa (Medicago sativa)

To identify amplified fragment length polymorphism (AFLP) markers associated with resistance or susceptibility of alfalfa to common leafspot (CLS) caused by the fungus Pseudopeziza medicaginis (Dermateaceae), bulked segregant analysis was conducted based on an F(1(M × M)) population of 93 plants and a BC(1)S population of 91 plants. Three AFLP markers, ACTCAA(R206), TAGCAC(R185), and GGACTA(S264), were found to be associated with CLS resistance or susceptibility. All three markers were found at significantly different frequencies (71.9, 80.3 and 91.8%) compared to resistant or susceptible plants in the original population. Subsequently, these three AFLP markers were converted into three SCAR markers, ACTCAA(R136), TAGCAC(R128) and GGACTA(S254), which are easier to employ in breeding programs. The three SCAR markers were used in a randomly selected population with 50% resistance; the probability of finding one resistant plant was increased to 67.3, 66.7 and 90.0% with markers ACTCAA(R136), TAGCAC(R128) and GGACTA(S254), independently. If two of the SCAR markers were used simultaneously, the probability would be higher than 89%. The three SCAR markers identified in this study would be applicable for selection for CLS resistance in alfalfa breeding programs. Moreover, the genetic analysis indicated that CLS resistance in alfalfa is conferred by a single dominant gene.

Cleavage of E2F-1-regulating proteins and activation of E2F-1 during CD95-induced death of thymocytes

The CD95 death receptor activates caspases that cleave a variety of intracellular substrates, including cell cycle control proteins. However, the significance of this cleavage for the induction of apoptosis is unclear. In this study, CD95-induced cleavage of the G1/S checkpoint regulator proteins, retinoblastoma protein (pRb) and murine-double-minute-2 (mdm-2), was associated with an increased protein concentration of a key transcription factor, E2F-1, which is regulated by both of them. Furthermore, DNA-binding activity to E2F sites is increased. In thymocytes, CD95-induced apoptosis was associated with increased E2F-1 DNA-binding activity, while thymocytes that lacked E2F-1 were less susceptible to CD95-induced apoptosis. We conclude that the G1/S checkpoint is an important target of CD95 signalling. CD95-activated caspases cleave regulator proteins to increase E2F-1 activity, and inappropriate activation of E2F-1 is part of the mechanism of CD95-induced apoptosis.

The synaptic activity of HsDmc1, a human recombination protein specific to meiosis

Human Dmc1 protein, a meiosis-specific homolog of Escherichia coli RecA protein, has previously been shown to promote DNA homologous pairing and strand-exchange reactions that are qualitatively similar to those of RecA protein and Rad51. Human and yeast Rad51 proteins each form a nucleoprotein filament that is very similar to the filament formed by RecA protein. However, recent studies failed to find a similar filament made by Dmc1 but showed instead that this protein forms octameric rings and stacks of rings. These observations stimulated further efforts to elucidate the mechanism by which Dmc1 promotes the recognition of homology. Dmc1, purified to a state in which nuclease and helicase activities were undetectable, promoted homologous pairing and strand exchange as measured by fluorescence resonance energy transfer (FRET). Observations on the intermediates and products, which can be distinguished by FRET assays, provided direct evidence of a three-stranded synaptic intermediate. The effects of helix stability and mismatched base pairs on the recognition of homology revealed further that human Dmc1, like human Rad51, requires the preferential breathing of A small middle dotT base pairs for recognition of homology. We conclude that Dmc1, like human Rad51 and E. coli RecA protein, promotes homologous pairing and strand exchange by a "synaptic pathway" involving a three-stranded nucleoprotein intermediate, rather than by a "helicase pathway" involving the separation and reannealing of DNA strands.

Neutrophil lactoferrin release induced by IgA immune complexes differed from that induced by cross-linking of fcalpha receptors (FcalphaR) with a monoclonal antibody, MIP8a

The human IgA Fc receptor (FcalphaR, CD89) plays an important role in host defence against invading pathogens. To study the properties of the receptor, 12 MoAbs, namely, MIP7c, MIP8a, MIP9a, MIP10c, MIP11c, MIP14b, MIP15b, MIP38c, MIP59c, MIP65c, MIP68b and MIP71a, were generated. The inhibitory effects of the antibodies on FcalphaR functions were tested. Three of the antibodies, MIP7c, MIP8a and MIP59c, were able to block up to 90% of soluble FcalphaR binding to IgA-coated beads and 70-80% of neutrophil phagocytosis of IgA immune complexes (IC). MIP8a could also inhibit IgA IC-induced neutrophil lactoferrin release, while cross-linking of FcalphaR with MIP8a and anti-mouse IgG could elicit neutrophil lactoferrin release. However, IgA IC-induced lactoferrin release required both extracellular calcium and magnesium, whereas MIP8a-induced release did not require extracellular magnesium and only partially required extracellular calcium. In addition, the time course of IgA IC-induced lactoferrin release was slow. Lactoferrin was not detectable if the incubation time was less than 0.5 h. In contrast, MIP8a-induced lactoferrin release was fast. Lactoferrin could be detected within 5 min of incubation. Therefore, neutrophil lactoferrin release induced by IgA IC differed from that induced by cross-linking of FcalphaR with MIP8a.

CD95/Fas signaling in T lymphocytes induces the cell cycle control protein p21cip-1/WAF-1, which promotes apoptosis

Ligation of CD95 on T lymphocytes resulted in the up-regulation of a cell cycle control protein, p21cip-1/WAF-1, an inhibitor of cyclin-dependent kinases. This up-regulation was completely blocked by the cysteine protease inhibitor Z-VAD-fmk (benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone), whereas DEVD-CHO (succinyl-Asp-Glu-Val-Asp-aldehyde), a caspase 3 inhibitor, had no effect. In Faslpr-cg mice, a point mutation in the death domain of CD95 results in failure to recruit FADD (Fas-associated death domain), and in the present study this mutation prevented both CD95-mediated apoptosis and p21cip-1/WAF-1 induction. During apoptotic cell death due to irradiation, p21cip-1/WAF-1 is up-regulated by a p53-dependent pathway that responds to DNA damage. However, CD95-induced up-regulation of p21cip-1/WAF-1 in T cells was p53-independent. T cells deficient in p21cip-1/WAF-1 were less susceptible to CD95-induced apoptosis. We conclude that in T cells, ligation of CD95 and activation of caspases cause the induction of p21cip-1/WAF-1, which acts to promote cell death.

Catalytic cleavage of the androgen receptor messenger RNA and functional inhibition of androgen receptor activity by a hammerhead ribozyme

Androgen receptor (AR) plays a key role in cell growth both in the normal prostate and in prostate cancer. Androgen ablation and prolonged antiandrogen therapy can give rise to AR-dependent prostate tumors, which nonetheless can grow in the androgen-deprived milieu. Here we describe the ribozyme approach to selectively degrading the AR mRNA and thereby inhibiting AR function. A trans-acting hammerhead ribozyme was designed to cleave the rat AR mRNA at the position +1827/ 1828, a region predicted to be minimally involved in generating stable secondary structures. Using AR mRNA fragments as substrates, it was established that this ribozyme can specifically cleave the RNA target in a sequence-specific manner. Kinetic experiments determined a Km for the substrate of 77 nM and a kcat/Km value of 1.8 x 10(7) M(-1) x min(-1), suggesting a catalytic efficiency similar to that of protein enzymes such as the relatively nonspecific ribonuclease A and a sequence-specific endonuclease EcoRI. Transient cotransfections of prostate-derived PC3 cells with three plasmids, an AR-inducible chloramphenicol acetyltransferase (CAT) reporter, an AR expression vector, and a ribozyme expression vector, showed that the ribozyme was capable of reducing the functional activity of AR. At an equimolar ratio of the AR expression plasmid to ribozyme expression plasmid, androgen-inducible CAT activity was inhibited 70%. Similar extents of inhibition were also observed at the cellular mRNA level using ribonuclease protection assays, indicating that the ribozyme functioned as an AR mRNA cleaving enzyme in cellulo. Immunocytochemical examination revealed a decline of AR immunoreactivity in ribozyme-transfected cells. In addition, no morphologically detectable cellular abnormalities were associated with ribozyme expression, indicating the absence of deleterious side effects. These results offer a new avenue for the control of AR function and cell growth, especially in the case of androgen-resistant, but AR-dependent, prostate cancer cells.