Glucocorticoids and aging

In this review we analyze the morphologic changes, hypothalamic-pituitary-adrenal (HPA) axis functions, glucocorticoid (GC) receptors, and steroidogenic enzyme activities in both animals and humans during aging. In rodent studies, older animals tend to show: 1) hypertrophy of adrenal zona fasciculata (ZF) cells; 2) neuronal loss in the hypothalamic area; 3) loss of GC receptors in the hippocampus; 4) raised circulating adrenocorticotropic hormone (ACTH) and GC levels, and increased release of corticotropin-releasing hormone from the hypothalamus; 5) reduced suppression of endogenous GC secretion after administration of dexamethasone; 6) decreased attenuation of response to chronic stress; and 7) increased activity of P450scc and 21-hydroxylase. According to the GC cascade hypothesis, stress and GCs facilitate the aging process in rats. Stress induces downregulation of GC receptors in the hippocampus, then impairs GC feedback on stress-induced HPA axis activation. Finally, an increase in the basal level of corticosterone and extended GC secretion following stress occurs. Because activation of the hippocampus decreases HPA axis function, the unrestrained elevation of GC concentration and the reduction in the level of GC receptors in the hippocampus may gradually weaken the feedback mechanisms and halt the response to stress. In humans, there are conflicting reports of HPA axis function during aging, so it is difficult to make a final conclusion regarding the relationship between aging and HPA axis function.     

An experimental study of the dynamics of the curing process of sheet molding compound (SMC) paste

The dynamic curing behavior of sheet molding compound (SMC) has been investigated by using a cylindrical cure reactor. Both thermal and mechanical responses were determined for R-25 SMC paste. The responses from this material were analyzed to determine the chemical and physical transformations that occur during the SMC molding process. The thermal response was obtained from a thermocouple placed along the centerline of the paste sample in the cure reactor. The thermal history at this location shows distinctive stages associated with heat transfer and crosslinking reactions during the cure cycle. The R-25 paste has a precure time of 160 seconds, a reaction time of 25 seconds, and a temperature rise of 134°C. The mechanical response describes the volume change and the pressure of the paste. The displacement curve shows volume changes due to thermal expansion, cure shrinkage, and thermal contraction during the course of a cure cycle. We found a less than 1% shrinkage during the reaction of the R-25 paste. The pressure response of the paste was found to parallel the volume transformation, although it also is strongly influenced by mechanical interactions between the press and the paste.     

Lossless image coding using adaptive, switching algorithm with automatic fuzzy context modelling

A switching adaptive predictor (SWAP) with automatic fuzzy context modelling is proposed for lossless image coding. Depending on the context of the coding pixel, the SWAP encoder switches between two predictors: the adaptive neural predictor (ANP) and the texture context matching (TCM) predictor. The ANP is known to perform well and gives small prediction errors except for pixels around edges. For areas with edges, TCM is used. To decide which is to be used, a switching criterion is proposed to pick out pixels around edges effectively. With the switching predictor structure, small prediction errors can be achieved in both slowly varying areas and edges. Furthermore, the use of the so-called fuzzy context clustering for prediction error refinement is proposed. The proposed compensation mechanism is proved to be very useful through experiments. It further improves the bit rates by, on average, 0.2 bpp in test images. The experiments also show that an average improvement of 0.3 and 0.05 bpp in first-order entropy can be achieved when the proposed switching predictor is compared with the gradient adjusted predictor and a six-order edge directed predictor, respectively. Moreover, the lossless image coder built upon the proposed algorithm also provides lower bit rates than the state-of-the-art context-based, adaptive, lossless image coding (CALIC) system and is comparable to that obtained by the highly complex two-pass coder called TMW     

Fast removal of Pb(II) and Cu(II) from contaminated water by groundwater treatment waste: impact of sorbent composition

ABSTRACT

A non-hazardous groundwater treatment waste (GWTW) was examined as a low-cost sorbent for Pb(II) and Cu(II) ions. The content of the dominant elements in GWTW was as follows: 78% Fe₂O₃, 7.4% P₂O₅, 7.4% CaO and 5.2% SiO₂. The removal of Pb(II) and Cu(II) was fast, and more than 67–95% of ions were accumulated by GWTW during the first 3 min. The sorption capacity of GWTW depends on solution pH, concentration and temperature. Equilibrium data fitted well with Langmuir–Freundlich and Langmuir-partition models. The inherently formed nano-adsorbent could be utilized for the treatment of water contaminated with Pb(II) and Cu(II) ions.     

Experimental and analytical procedures for flow dynamics of sheet molding compound (SMC) in compression molding

A package of procedures have been developed to collect and analyze the response of dynamic variables such as pressure, temperature, and mold separation during the compression molding of Sheet Molding Compound (SMC). From the dynamic responses, the molding process was found to consist of two regions: the flow and the subsequent curing reaction region. With an R-25 formulation and a mold closing rate of 30 mm/s, these two regions are well separated and the average flow time is not significantly affected by the maturation time for the material up to 30 days. Several mechanical parameters were estimated based on relatively simple flow models. The relationship between the press force, mold separation, and mold closing rate is found to be sensitive to the restrictions of the flow.     

Early development in males with Fragile X syndrome: a review of the literature

This article reviews the current bibliographic knowledge on early neurobehavioral development and milestones in Fragile X syndrome (FraX), with emphasis on males affected by the condition. Three broad areas of early development were examined: (1) gross and fine motor, (2) speech and language, and (3) social. The result of the current review indicates very limited information on the developmental milestones in all three areas. The scarce literature on motor development shows that in FraX there is an early developmental delay. Research on speech and language demonstrates pervasive deficits in conversational skills and severe developmental delay, with increasing discrepancy between language level and chronological age in young males with FraX. Finally, deficits in social development in FraX include abnormal gaze, approach and avoidance conflict, and high incidence of autistic spectrum disorders.     

Compression molding of biodegradable drug‐eluting implants for sustained release of metronidazole and doxycycline

The purpose of this report was to develop solvent‐free biodegradable drug‐eluting implants that provide sustained release of metronidazole and doxycycline. The drug‐eluting implants were prepared using the compression molding technique. To fabricate the implants, polylactide‐polyglycolide copolymers were premixed with metronidazole or doxycycline. The mixture was then compression molded and sintered to form implants of various sizes and geometries. An elution method and an HPLC assay were used to characterize the in vitro release rates of the antibiotics over a 28‐day period. A bacterial inhibition test was also carried out to determine the bioactivity of released antibiotics. The concentrations of both metronidazole and doxycycline were much greater than the minimum inhibitory concentration of Escherichia coli for up to 3 and 4 weeks, respectively, and the bioactivities of the antibiotics remained high after the fabrication process. Furthermore, the initial burst could be minimized and the release rate could be reduced by increasing the size of the implants and by adopting low drug to polymer ratios. By using this compression molding technique and appropriate processing parameters, we will be able to fabricate biodegradable implants of various types of antibacterial drugs for long‐term local deliveries. Eventually, biodegradable drug‐eluting implants may be used to treat various periodontal diseases. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A new LMI condition for robust stability of discrete-time uncertain systems

In this paper, a new robust stability condition is derived for uncertain discrete-time linear systems with convex polytopic uncertainties. The condition is expressed in terms of a set of linear matrix inequalities (LMIs) involving only the vertices of the polytope domain. It enables us to determine robust stability of uncertain systems easily by solving some LMIs. A rigorous proof is given to show that an interesting result appeared recently is a special case of the proposed condition. Numerical examples also demonstrate the merit of the present condition in the aspect of conservativeness over other results in the literature.     

Inhibition of gastric emptying and intestinal transit by amphetamine through a mechanism involving an increased secretion of CCK in male rats

1. The effect of amphetamine on gastrointestinal (GI) transit and the plasma levels of cholecystokinin (CCK) were studied in male rats. 2. Gastric emptying was inhibited both acutely and chronically by the administration of amphetamine. GI transit was decreased by the acute administration of amphetamine but not affected by the chronic administration of amphetamine. 3. Plasma CCK levels were increased dose-dependently by amphetamine. 4. Proglumide, a CCK receptor antagonist, prevented amphetamine-induced inhibition of gastric emptying and the decrease in GI transit in male rats. 5. The selective CCK(A) receptor antagonist, lorglumide, dose-dependently attenuated the amphetamine-induced inhibition of gastric emptying in male rats. In contrast, the selective CCK(B) receptor antagonist, PD 135,158, did not reverse the effect of amphetamine on gastric emptying. 6. Both lorglumide and PD 135,158 reversed the inhibitory effect of amphetamine on GI transit in male rats. 7. These results suggest that amphetamine-induced inhibition of gastric emptying and intestinal transit is due in part to a mechanism associated with the hypersecretion of endogenous CCK.