2,243 publications from this institution
Reinforced concrete structures are normally exposed to various aggressive environmental conditions; thus it is essential to protect the steel reinforcement from corrosion and the concrete from degradation. This experimental study is aimed at optimising the physico-mechanical properties of reinforced concrete by using iron mill scale as a replacement for cement. Reinforced cement mortars and concrete specimens with and without the addition of iron mill scale were partially immersed in 3·5% w/w sodium chloride solution for 17 months and 130 d, respectively. The mill scale was added to the aforementioned cementitious composites in proportions of 5% and 10% by weight of cement. Its effect on chloride penetration resistance was evaluated using various standardised and non-standardised experimental techniques. The results showed that the additive increased the resistance of reinforced cementitious composites to chloride penetration, reduced the corrosion of steel reinforcement and improved the compressive strength of concrete. Furthermore, iron mill scale decreased the concentration of chloride ions in cement mortars which were partially immersed in sodium chloride solution.
The function of the hypothalamic-adenohypophyseal unit was tested in 2 groups of rhesus monkeys before and at periodic intervals after the administration of 2400 and 4000 rads cranial radiation. This therapy was given in 10 fractions over a 2-week period. Plasma TSH, basally and after TRH administration, and LH and FSH, before and after gonadotropinreleasing hormone stimulation, were normal up to 1 yr after radiation. Plasma GH at the basal state and after arginine and L-dopa stimulation was also normal. An insulin tolerance test, however, demonstrated a blunted GH response at a dose (0.1 U/kg) that caused brisk stimulation of GH secretion in normal control monkeys. A larger dose of insulin (0.2 U/kg) resulted in ample secretion of GH in these animals, suggesting decreased hypothalamic sensitivity to insulin in treated animals. The measurement of GH every 20 min for 24 h in animals treated with 4000 rads showed a dramatically altered secretory pattern of GH 1 yr after radiation. GH secretory spikes were markedly decreased in both frequency and amplitude, suggesting a reduction in the normal daily production of GH. (J Clin Endocrinol Metab54: 1135, 1982)
What is 'Primary Generalized Glucocorticoid Resistance' (PGGR)?PGGR means that all tissues in an organism have decreased sensitivity or "resistance" to the natural glucocorticoid, in us humans, cortisol.What biological processes underlie this "resistance" to cortisol?Because this resistance includes the hypothalamicpituitary-adrenal (HPA) axis negative feedback regulatory centers in the brain and pituitary gland, this axis is activated to "overcome" or compensate for the glucocorticoid action defect (Figure 1).The production of hypothalamic corticotropin-releasing hormone (CRH), arginine-vasopressin (AVP) and pituitary adrenocorticotropic hormone (ACTH) increase and the adrenal cortices hyperfunction, secreting large amounts of cortisol, adrenal steroid precursors and adrenal androgens.The adrenal steroid precursors include deoxy-corticosterone and corticosterone, both of which, as well as cortisol, have sodium-retaining activity through the mineralocorticoid receptor, which is normal in patients with cortisol resistance.Thus, the patient tissues are exposed to elevated levels of adrenal androgens and mineralocorticoids, which result in manifestations of hyperandrogenism and hypermineralocorticoidism.What are these manifestations of hyperandrogenism and hypermineralocorticoidism?These manifestations include acne, hirsutism, oligoamenorrhea, male-pattern baldness, and hypofertility in women and virilization in children, and hypertension and alkalosis with or without hypokalemia in both sexes, respectively.
Concerns over anxiety and depressive symptoms in children with premature adrenarche (PA) have been recently raised. However, to date, most relevant studies are on a small number of girls. In this cross-sectional study, 82 pre-pubertal children (66 girls and 16 boys) diagnosed with PA, were compared to 63 control children regarding their psychological characteristics and hypothalamic–pituitary–adrenal (HPA) axis function, as assessed by salivary cortisol measurement. Symptoms of anxiety and depression were assessed by child self-report (Spence Children’s Anxiety Scale (SCAS) and Depression self-rating scale for Children (DSRS)) and parent-report (Child Behaviour Checklist (CBCL)) tests validated for the Greek population. Salivary cortisol levels were determined directly after awakening (approximately 7am) and evening (8pm) of the same day. Morning serum DHEAS levels were assessed in PA children. Girls with PA scored significantly higher on anxiety (p = .016) and depression (p =.039) scales than controls. No group differences were noted for parent reports and children’s salivary cortisol concentrations. Boys with PA did not demonstrate significant differences in any of the aforementioned parameters. Our findings suggest that girls with PA may be at higher risk for reporting symptoms of anxiety and depression than their non-PA peers. HPA axis dysregulation in this population was not documented.
The squirrel monkey, a New World primate, has plasma cortisol levels roughly 12 times those in Old World primates, such as the cynomolgus monkey, and man. Two mechanisms are possible to maintain this high plasma cortisol level: an increased cortisol production rate (PR) and a decreased cortisol MCR. The cortisol MCR in the squirrel monkey is half that in the cynomolgus monkey [65 ± 3 vs. 123 ± 3 liters/M2- day (mean ± SE), respectively; P < 0.001]. The cortisol PR, however, is 6 times higher in the squirrel monkey than in the cynomolgus monkey (199 ± 21 vs. 32 ± 6 mg/M2• day; P< 0.001). The mild adrenal gland enlargement of the squirrel monkey (320 ± 22 us. 197 ± 10 mg adrenal/kg BW in the cynomolgus monkey; P < 0.001) does not appear to account entirely for the 6-fold increase in the cortisol PR. These findings suggest an increased cortisol biosynthetic efficiency in the squirrel monkey. This was examined by measuring the activity of four adrenal microsomal enzymes. 3β-Hydroxysteroid dehydrogenase-isomerase activities are similar in the squirrel and cynomolgus monkeys [10.5 ± 0.15 vs. 10.2 ± 0.51 nmol-min/mg protein (mean ± SE), respectively], whereas 17-hydroxylase activity is slightly higher in the cynomolgus monkey (10.5 ± 0.09 vs. 9.4 ± 0.52 nmol-min/mg protein in the squirrel monkey; P < 0.05). The activity of 21- hydroxylase, however, is 4 times higher in the squirrel monkey (23.9 ± 0.26 us. 6.4 ± 0.23 nmol-min/mg protein in the cynomolgus monkey; P < 0.001), and 17,20-desmolase activity is significantly lower in the squirrel monkey (24.7 ± 1.98 vs. 37.5 ± 1.86 pmol-min/mg protein in the cynomolgus monkey; P < 0.0025). Plasma ACTH concentrations are similar in squirrel and cynomolgus monkeys [8.6 ± 1.0 vs. 10.3 ± 4.0 pg/ml (mean ± SE), respectively]. We conclude that the squirrel monkey maintains high plasma cortisol levels mainly by an increased cortisol PR, which may be facilitated by alterations in the activity of the cortisol biosynthetic enzymes.
A bstract : The functions of the hypothalamic‐pituitary‐ovarian and ‐adrenal axes are intertwined, and molecular defects in either axis may cause ovarian dysfunction. Advances in molecular genetics have allowed new insights into the pathophysiology of ovarian disorders. Specific gene mutations causing delayed puberty and/or ovarian failure, and heterosexual or isosexual precocious puberty have recently been described. The molecular insights gained into ovarian dysfunction have already led to rational therapies for some of these conditions.
Conflicts and wars, particularly prevalent in regions such as Africa, the Middle East and Asia, have profound and multifaceted effects on individuals, spanning socioeconomic, medical and psychological realms. The present review delves into the intricate interplay between genetics, epigenetics and the experiences of individuals, particularly children, in conflict zones. Genetics, the study of inherited traits, and epigenetics, the study of how environmental factors influence gene expression, jointly shape the development and response to trauma of an individual. While traditionally, genes were considered the sole determinants of traits, epigenetic modifications reveal the significant role of environmental factors. Children in war zones are particularly vulnerable, suffering from a myriad of physical and psychological traumas, including post‑traumatic stress disorder and depression. Moreover, exposure to violence during critical developmental periods can have transgenerational effects, affecting the mental and physical health of subsequent generations. Recent research highlights epigenetic changes in individuals affected by historical traumas, such as the Holocaust, demonstrating how parental trauma can influence offspring. Interventions targeting epigenetic mechanisms show promise in mitigating the effects of trauma. Narrative exposure therapy and other psychological interventions have been shown to induce epigenetic changes associated with memory and trauma processing, offering hope for affected individuals. Additionally, environmental influences during critical periods, such as famine during adolescence, have been linked to long‑term health outcomes, including the risk of developing colorectal cancer. Herein, the intricate interplay between genetics, epigenetics and environmental factors in shaping individual responses to trauma is underscore. Further research on a larger scale is warranted to validate and expand upon these findings, offering insight into potential avenues for intervention and support for individuals affected by conflict‑related trauma.
The variability in the seismic demand and capacity of a steel frame having beam hinges with uncertain properties is investigated through Incremental Dynamic Analysis (IDA) using both Monte Carlo simulation and approximating techniques. The 9-story steel moment-resisting frame is modeled using parameterized moment-rotation relationships with quadrilinear backbones for the beam plastic-hinges. The uncertain properties of the backbones include the yield moment, the post-yield hardening ratio, the end-of-hardening rotation, the slope of the descending branch, the residual moment capacity and the ultimate rotation reached. IDA is employed to accurately assess the seismic performance of the model for any combination of the parameters by performing multiple nonlinear time history analyses for a suite of ground motion records. IDA sensitivity analysis reveals the yield moment and the two rotational-ductility parameters to be the most influential for the frame behavior. To propagate the parametric uncertainty to the actual seismic performance we employ a) Monte Carlo simulation with latin hypercube sampling, b) point-estimate and c) first-order second-moment techniques, thus offering competing methodologies that represent different compromises between speed and accuracy. The final results provide firm ground for challenging current assumptions in seismic guidelines on using a mean-parameter model to estimate the mean seismic performance and employing the well-known square-root-sum-of-squares rule to combine aleatory randomness and epistemic uncertainty.
