Mathematical modeling of atherogenesis: Atheroprotective role of HDL.

Atherosclerosis is a chronic inflammatory cardiovascular disease in which arteries harden through the build-up of plaques. This work is devoted to the mathematical modeling and analysis of the inflammatory process of atherosclerosis. We propose a mathematical model formed by three coupled partial differential equations of reaction-diffusion type. We take into account three key-role players: the inflammatory immune cells, the inflammatory cytokines and the oxidized low density lipoproteins. A stability analysis of the kinetic system is performed. It leads to the presence of three stable fixed points relevant to appropriate biological states of atherogenesis; no inflammation, stabilized inflammation (stable plaque) and advanced inflammation (vulnerable plaque). The cases that may occur are subject to the variation of the parameters values. A detailed discussion showing how the model fits the biological phenomena is then established. We investigate as well the existence of solutions of traveling waves type along with numerical simulations that show the wave propagation in different cases. This shows that the inflammatory process propagates inside the intima as a traveling wave. Then, we consider the effect of high density lipoprotein (HDL) on the atherosclerotic plaque formation. To do that, we elaborate a map that determines the level of risk of plaque formation with respect to the prevalence of HDL in the blood. These results confirm but also generalize previous results published in the literature. They also give a deeper understanding to the propagation of the inflammation inside the artery in terms of the interplay among the different main players in the whole process.

Rapid spectral variability of a giant flare from a magnetar in NGC 253.

Magnetars are neutron stars with extremely strong magnetic fields (1013 to 1015 gauss)1,2, which episodically emit X-ray bursts approximately 100 milliseconds long and with energies of 1040 to 1041 erg. Occasionally, they also produce extremely bright and energetic giant flares, which begin with a short (roughly 0.2 seconds), intense flash, followed by fainter, longer-lasting emission that is modulated by the spin period of the magnetar3,4 (typically 2 to 12 seconds). Over the past 40 years, only three such flares have been observed in our local group of galaxies3-6, and in all cases the extreme intensity of the flares caused the detectors to saturate. It has been proposed that extragalactic giant flares are probably a subset7-11 of short γ-ray bursts, given that the sensitivity of current instrumentation prevents us from detecting the pulsating tail, whereas the initial bright flash is readily observable out to distances of around 10 to 20 million parsecs. Here we report X-ray and γ-ray observations of the γ-ray burst GRB 200415A, which has a rapid onset, very fast time variability, flat spectra and substantial sub-millisecond spectral evolution. These attributes match well with those expected for a giant flare from an extragalactic magnetar12, given that GRB 200415A is directionally associated13 with the galaxy NGC 253 (roughly 3.5 million parsecs away). The detection of three-megaelectronvolt photons provides evidence for the relativistic motion of the emitting plasma. Radiation from such rapidly moving gas around a rotating magnetar may have generated the rapid spectral evolution that we observe.

Does using testicular sperm retrieval rather than ejaculated spermatozoa improve reproductive outcomes in couples with previous ART failure and poor ovarian response? A case-controlled study.

The objective of this study was to assess whether testicular-retrieved spermatozoa improve reproductive outcomes compared to fresh ejaculate in women with poor ovarian response and a history of previous ART failure. The study was performed as a retrospective case-control study at a university-based reproductive center in Montreal, Quebec, Canada. Eighteen poor-responder patients were matched 3 : 1 with 54 controls. Poor responders were defined as those with ≤3 oocytes retrieved at oocyte pickup. Cases were identified as poor responders, and only those with previous IVF failure(s) as an indication for testicular-retrieved spermatozoa were included. Controls were age and cycle attempt number matched. All patients were included only once. From January 1, 2009 to December 31, 2015, all patients and controls underwent an IVF cycle using ICSI with either testicular spermatozoa or ejaculated spermatozoa, respectively. Outcomes included live birth rate, pregnancy rate, miscarriage rate, oocyte number, and embryo transfer (ET) day. The results showed live birth rates, pregnancy rates, and miscarriage rates were similar. There were fewer day 2 ETs (8.5% vs. 48.6%, p = 0.01) and more day 5 blastocyst transfers (25.0% vs. 5.4%, p = 0.05) in the testicular sperm retrieval group compared to controls and thus an overall suggestion of better embryo quality in the testicular sperm group. Overall, however, the use of testicular sperm retrieval appears to add little. Women with poor ovarian response typically have a poor prognosis with respect to live birth rates, and this is further supported in this study. The suggestion of better embryo quality in the testicular-retrieved sperm group would need to be further assessed in a larger multicentered study.

Characteristics of The Narrow Spectrum Beams Used in the Secondary Standard Dosimetry Laboratory at the Lebanese Atomic Energy Commission.

The Secondary Standard Dosimetry Laboratory at the Lebanese Atomic Energy Commission has different calibration methods for various types of dosimeters used in industrial, military and medical fields. The calibration is performed using different beams of X-rays (low and medium energy) and Gamma radiation delivered by a Cesium 137 source. The Secondary Standard Dosimetry laboratory in charge of calibration services uses different protocols for the determination of high and low air kerma rate and for narrow and wide series. In order to perform this calibration work, it is very important to identify all the beam characteristics for the different types of sources and qualities of radiation. The following work describes the methods used for the determination of different beam characteristics and calibration coefficients with their uncertainties in order to enhance the radiation protection of workers and patient applications in the fields of medical diagnosis and industrial X-ray. All the characteristics of the X-ray beams are determined for the narrow spectrum series in the 40 and 200 keV range where the inherent filtration, the current intensity, the high voltage, the beam profile and the total uncertainty are the specific characteristics of these X-ray beams. An X-ray software was developed in order to visualize the reference values according to the characteristics of each beam.

The first pulse of the extremely bright GRB 130427A: a test lab for synchrotron shocks.

Gamma-ray burst (GRB) 130427A is one of the most energetic GRBs ever observed. The initial pulse up to 2.5 seconds is possibly the brightest well-isolated pulse observed to date. A fine time resolution spectral analysis shows power-law decays of the peak energy from the onset of the pulse, consistent with models of internal synchrotron shock pulses. However, a strongly correlated power-law behavior is observed between the luminosity and the spectral peak energy that is inconsistent with curvature effects arising in the relativistic outflow. It is difficult for any of the existing models to account for all of the observed spectral and temporal behaviors simultaneously.

Mycotic aneurysm of the celiac trunk: radical resection and reconstruction without prosthetic material.

The Authors report a case of mycotic aneurysm of the celiac trunk, originating from bacterial endocarditis on the mitral valve. The technique was excision and revascularization without interposition of any material: for the moment it is the first time that a mycotic aneurysm of the celiac trunk is treated in this manner. The post-operative course was normal.

FCE 22101 and FCE 22891: in-vitro antibacterial activity at concentrations simulating human plasma levels following intravenous, intramuscular and oral administration.

The plasma concentrations of FCE 22101 observed following slow intravenous infusions (1 and 4 h), intramuscular injection and after oral administration of the prodrug FCE 22891 were simulated in a glass chamber containing bacterial cultures. The bacteria used were Staphylococcus aureus ATCC 13709, Staph. aureus 2101 (methicillin-resistant), Streptococcus faecium ATCC 8043, Escherichia coli ATCC 12407, Enterobacter cloacae 1321E and Ent. cloacae P99 (cefazolin-resistant). Addition of FCE 22101 was found to result in a reduction in number of all bacterial strains except Str. faecium, with which only bacteriostasis was observed.

Activity of FCE 22891 compared with cefuroxime axetil and cefixime in pulmonary and subcutaneous infections in mice.

The therapeutic activity of FCE 22891 was compared with that of two new oral cephalosporins, cefuroxime axetil and cefixime against Streptococcus pneumoniae respiratory infection and subcutaneous abscesses induced by mixed aerobes and anaerobes in mice. In experimental pneumonia FCE 22891 was the most active antibiotic. In aerobic abscesses FCE 22891 proved the most active agent in infections induced by methicillin susceptible and resistant Staphylococcus aureus while all three compounds were very active, against Str. pyogenes. In abscesses caused by Gram-negative bacteria, FCE 22891 showed good and constant efficacy. Cefixime was the most active drug against the two susceptible strains of Escherichia coli and Enterobacter cloacae and also against resistant Esch. coli but was inactive against a strain of Ent. cloacae that produced cephalosporinase. Cefuroxime axetil was less active than the other two drugs against Gram-negative bacteria with adequate efficacy only against a susceptible strain of Ent. cloacae. FCE 22891 was more effective than cefixime and cefuroxime axetil in preventing and reducing the size of abscesses induced by Bacteroides fragilis 101. We conclude that FCE 22891, despite its short half life of 6 min in mice, exerts comparable and sometimes better activity than the two oral cephalosporins characterized by longer half lives.