Contents
The effects of glucocorticoids on both foetal canine lung and endogenous serum cortisol concentration have not been clearly delineated. Therefore, we aimed to investigate whether maternal ...corticosteroid treatment can alter maternal and neonatal cortisol profile and improve neonatal vitality. We allocated six bitches of different breeds and their neonates into two groups: control group (CONT) – maternal administration of saline solution at 55 days post‐ovulation (n = 3); and betamethasone group (BETA) – administration of a single dose of 0.5 mg/kg betamethasone (Celestone Soluspan®) at 55 days post‐ovulation (n = 3). Caesarean sections were scheduled for day 63 after ovulation. However, BETA group dams showed precocious signs of labour, and c‐sections were performed at 58 days post‐ovulation. Maternal and neonatal evaluations were performed periodically between betamethasone administration and birth, respectively. Neonates from both groups presented unsatisfactory (<5) Apgar score at birth. However, in spite of an earlier improvement on vitality found on CONT group and the premature delivery on BETA group, both groups showed acceptable Apgar score 120 min after birth. Neonatal cortisol concentrations were higher on CONT group compared to BETA group at birth. In addition, a gradual decrease on maternal cortisol concentrations was observed in the BETA group from treatment until parturition. These findings suggest that despite the down‐regulation on the hypothalamic‐pituitary‐adrenal axis and the induction of premature delivery, betamethasone treatment was able to provide similar vitality when compared to the untreated neonates born at term.
There are limited data concerning blood gas parameters in neonatal dogs. Knowledge of the normal physiology may facilitate effective therapeutic intervention and potentially reduce neonatal ...mortality. This study examined acid-base parameters in pups born at normal parturition (n = 27) compared with those born after obstetrical assistance or caesarean operation (n = 13) and those born following oxytocin (OXY) administration for treatment of uterine inertia (n = 11). Pups were subjected to an objective scoring method of neonatal health adapted from use in humans (the Apgar score) at birth and again at 5 and 60 min after birth. Venous blood samples were collected at 5 and 60 min after birth for evaluation of blood gas parameters. At birth, all pups had low Apgar scores and a mixed acidosis. The base excess was lowest for pups delivered after OXY administration. The Apgar score improved for all pups after 5 min of birth and there was an improvement in carbon dioxide tension, base excess and venous blood pH at 1 h, although in all pups a metabolic acidosis persisted. These data provide an important insight into neonatal physiology and the variability of blood gas parameters in pups born at normal and abnormal parturition and provide the basis for clinical decision making following dystocia.
Clinical presentations of melioidosis, caused by
Burkholderia pseudomallei are protean, but the mechanisms underlying development of the different forms of disease remain poorly understood. In murine ...melioidosis, the level of virulence of
B. pseudomallei is important in disease pathogenesis and progression. In this study, we used
B. pseudomallei-susceptible BALB/c mice to determine the virulence of a library of clinical and environmental
B. pseudomallei isolates from Australia and Papua New Guinea. Among 42 non-arabinose-assimilating (ara
–) isolates, LD
50 ranged from 10 to > 10
6 CFU. There were numerous correlations between virulence and disease presentation in patients; however, this was not a consistent observation. Virulence did not correlate with isolate origin (i.e. clinical vs environmental), since numerous ara
– environmental isolates were highly virulent. The least virulent isolate was a soil isolate from Papua New Guinea, which was arabinose assimilating (ara
+). Stability of
B. pseudomallei virulence was investigated by in vivo passage of isolates through mice and repetitive in vitro subculture. Virulence increased following in vivo exposure in only one of eight isolates tested. In vitro subculture on ferric citrate-containing medium caused attenuation of virulence, and this correlated with changes in colony morphology. Pulsed-field gel electrophoresis and randomly amplified polymorphic DNA typing demonstrated that selected epidemiologically related isolates that had variable clinical outcomes and different in vivo virulence were clonal strains. No molecular changes were observed in isolates after in vivo or in vitro exposure despite changes in virulence. These results indicate that virulence of selected
B. pseudomallei isolates is variable, being dependent on factors such as iron bioavailability. They also support the importance of other variables such as inoculum size and host risk factors in determining the clinical severity of melioidosis.
There has been limited investigation of parturition in the bitch and there is little information published on clinical and obstetrical examination other than opinion and anecdote. While there are ...substantial data on haemodynamic and vascular changes during normal parturition in humans, little is known about the physiological events in the dog. This study was aimed at maternal haemodynamic changes occurring during normal parturition and to investigate how these were modified in bitches with dystocia (DYST) treated either medically or via assisted delivery and caesarean operation. Three groups of 10 bitches were investigated; those with normal parturition, those with DYST corrected by manipulative assistance or caesarean operation and those with uterine inertia treated by oxytocin administration. Heart rate, systolic and diastolic blood pressure, electrocardiogram and blood glucose concentration were measured pre-partum, intra-partum, immediately after parturition and 1 h later. Heart rate was high at all times throughout the study and the majority of bitches had normal sinus rhythm. Blood pressure was generally within the normal range, and although systolic and diastolic blood pressure was highest during the intra-partum period and sometimes during the immediate post-partum period, there were no significant differences between groups. All bitches had blood glucose concentrations within the normal range throughout the study although pre-partum concentrations were statistically lower than many of the other time periods. The study provides useful physiological data that will facilitate monitoring and clinical management of bitches throughout normal parturition and DYST.
We have grown 4 inch GaAs epitaxial layers of thickness ranging from 100 to 600 /spl mu/m. With such layers we made pixel X-ray detectors where each pixel is a p/sup +//i/n/sup +/ mesa structure in ...which the grown layer is the i region. The aim of this communication is to describe, prior to the evaluation of an image, the performances of such a detector in terms of homogeneity, reverse dark current, linearity, response time, dynamic range and charge collection efficiency. We shall also describe how the current induced by 100 kV X-rays in a detector made of a 115-/spl mu/m thick GaAs layer compares with that produced in the same conditions by a 1-mm thick CdTe detector.
During the initiation of neonatal pulmonary respiration, there is an exponential increase in reactive oxygen species that must be scavenged by antioxidant defences. However, neonate and preterm ...newborns are known to possess immature antioxidant mechanisms to neutralize these toxic effects. The purposes of this study were to compare the development of antioxidant system between preterm and term canine neonates and to evaluate the magnitude of acid–base balance during the initial 4 h of life. A prospective study was conducted involving 18 neonatal puppies assigned to Term Group (63 days of gestation; n = 5), Preterm‐57 Group (57 days of gestation; n = 8) and Preterm‐55 Group (55 days of gestation; n = 5). Neonates were physically examined through Apgar score and venous haemogasometry within 5 min, 2 and 4 h after birth. No difference on amniotic fluid and serum superoxide dismutase (SOD), glutathione peroxidase (GPx) and the marker of oxidative stress (thiobarbituric acid reactive substances; TBARS) was verified. Irrespective of prematurity, all neonates presented low vitality, hypothermia, acidosis, hypoxaemia and hypercapnia at birth. However, term puppies clinically evolved more rapidly than preterm newborns. During the course of the study, premature neonates presented more severe complications, such as prolonged hypoxaemia and even death. In conclusion, premature puppies have no signs of immature enzymatic mechanisms for controlling oxidative stress, although SOD and GPx may participate in achieving acid–base balance. Aside from initial unremarkable symptoms, premature puppies should be carefully followed up, as they are at high risk of succumbing to odds of prematurity.
We present photometric and spectroscopic observations of SN 2007if, an overluminous (M_V = -20.4), red (B-V = 0.16 at B-band maximum), slow-rising (t_rise = 24 days) type Ia supernova in a very faint ...(M_g = -14.10) host galaxy. A spectrum at 5 days past B-band maximum light is a direct match to the super-Chandrasekhar-mass candidate SN Ia 2003fg, showing Si II and C II at ~9000 km/s. A high signal-to-noise co-addition of the SN spectral time series reveals no Na I D absorption, suggesting negligible reddening in the host galaxy, and the late-time color evolution has the same slope as the Lira relation for normal SNe Ia. The ejecta appear to be well mixed, with no strong maximum in I-band and a diversity of iron-peak lines appearing in near-maximum-light spectra. SN2007 if also displays a plateau in the Si II velocity extending as late as +10 days, which we interpret as evidence for an overdense shell in the SN ejecta. We calculate the bolometric light curve of the SN and use it and the \ion{Si}{2} velocity evolution to constrain the mass of the shell and the underlying SN ejecta, and demonstrate that SN2007 if is strongly inconsistent with a Chandrasekhar-mass scenario. Within the context of a "tamped detonation" model appropriate for double-degenerate mergers, and assuming no host extinction, we estimate the total mass of the system to be 2.4 +/- 0.2 solar masses, with 1.6 +/- 0.1 solar masses of nickel-56 and with 0.3-0.5 solar masses in the form of an envelope of unburned carbon/oxygen. Our modeling demonstrates that the kinematics of shell entrainment provide a more efficient mechanism than incomplete nuclear burning for producing the low velocities typical of super-Chandrasekhar-mass SNeIa.
State of the art on epitaxial GaAs detectors Sun, G.C.; Mañez, N.; Zazoui, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2005, Volume:
546, Issue:
1
Journal Article
Peer reviewed
We first briefly review the performances for X-ray detection which are obtained using thin epitaxial GaAs layers. We then show that good detectors can be realized on thick and large area epitaxial ...GaAs layers which are now available, making them suitable for X-ray imaging. We finally discuss the main limitation imposed by the epitaxial nature of this new material and ways to overcome it.
We report observations of the optical counterpart of the long gamma-ray burst (LGRB) GRB 230812B, and its associated supernova (SN) SN 2023pel. The proximity (\(z = 0.36\)) and high energy ...(\(E_{\gamma, \rm{iso}} \sim 10^{53}\) erg) make it an important event to study as a probe of the connection between massive star core-collapse and relativistic jet formation. With a phenomenological power-law model for the optical afterglow, we find a late-time flattening consistent with the presence of an associated SN. SN 2023pel has an absolute peak \(r\)-band magnitude of \(M_r = -19.46 \pm 0.18\) mag (about as bright as SN 1998bw) and evolves on quicker timescales. Using a radioactive heating model, we derive a nickel mass powering the SN of \(M_{\rm{Ni}} = 0.38 \pm 0.01\) \(\rm{M_\odot}\), and a peak bolometric luminosity of \(L_{\rm{bol}} \sim 1.3 \times 10^{43}\) \(\rm{erg}\) \(\rm{s^{-1}}\). We confirm SN 2023pel's classification as a broad-lined Type Ic SN with a spectrum taken 15.5 days after its peak in \(r\) band, and derive a photospheric expansion velocity of \(v_{\rm{ph}} = 11,300 \pm 1,600\) \(\rm{km}\) \(\rm{s^{-1}}\) at that phase. Extrapolating this velocity to the time of maximum light, we derive the ejecta mass \(M_{\rm{ej}} = 1.0 \pm 0.6\) \(\rm{M_\odot}\) and kinetic energy \(E_{\rm{KE}} = 1.3^{+3.3}_{-1.2} \times10^{51}\) \(\rm{erg}\). We find that GRB 230812B/SN 2023pel has SN properties that are mostly consistent with the overall GRB-SN population. The lack of correlations found in the GRB-SN population between SN brightness and \(E_{\gamma, \rm{iso}}\) for their associated GRBs, across a broad range of 7 orders of magnitude, provides further evidence that the central engine powering the relativistic ejecta is not coupled to the SN powering mechanism in GRB-SN systems.
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