Search

The 11 β- hydroxysteroid dehydrogenase 1 (11 β-HSD1) is hypothesized to play a role in the pathogenesis of type 2 diabetes and its related complications. Because high glucocorticoid levels are a risk factor for metabolic disorders, 11β-HSD1 might be a viable therapeutic target. In this investigation, docking experiments were performed on the main constituents of Spondias mangifera (SM) oleanolic acid, β-amyrin, and β-sitosterol to ascertain their affinity and binding interaction in the human 11β-hydroxysteroid dehydrogenase-1 enzyme’s active region. The results of in vitro 11β HSD1 inhibitory assay demonstrated that the extract of S. mangifera had a significant (p < 0.05) decrease in the 11-HSD1% inhibition (63.97%) in comparison to STZ (31.79%). Additionally, a non-insulin-dependent diabetic mice model was used to examine the sub-acute anti-hyperlipidemic and anti-diabetic effects of SM fruits. Results revealed that, in comparison to the diabetic control group, SM fruit extract (SMFE) extract at doses of 200 and 400 mg/kg body weight considerably (p < 0.05 and p < 0.01) lowered blood glucose levels at 21 and 28 days, as well as significantly decreased total cholesterol (TC) and triglycerides (TG) and enhanced the levels of high-density lipoprotein (HDL). After 120 and 180 s of receiving 200 and 400 mg/kg SMFE, respectively, disease control mice showed significantly poorer blood glucose tolerance (p < 0.05 and p < 0.01). SMFE extract 200 (p < 0.05), SMFE extract 400 (p < 0.01), and Glibenclamide at a dosage of 5 mg/kg body weight all resulted in statistically significant weight increase (p < 0.01) when compared to the diabetic control group after 28 days of treatment. According to in silico, in vitro, and in vivo validation, SMFE is a prospective medication with anti-diabetic and hypoglycemic effects.

The one-step glycosylation of arylamines in acidic medium is extended to adenine derivatives for the first time, providing a considerable improvement over existing reactions. This method is used to prepare some rhamnospicamycin analogues containing different base moieties. Results suggest that this novel approach will be applicable to a wide range of carbohydrates and arylamines, possibly leading to a combinatorial library of analogues of spicamycin for the better understanding of the modes of action of this antitumour antibiotic family.

In this paper a technique for predicting odd-mode parametric oscillations from the analysis of exact pole-zero cancellations that take place in the frequency response obtained at some specific nodes of power amplifiers is presented. By using this technique the nature of parametric oscillations can be determined, which allows establishing a suitable strategy for circuit stabilization. The proposed methodology has been applied to the analysis and elimination of parametric odd-mode oscillations in an X- band two-stage MMIC power amplifier. The analysis has been complemented with the harmonic-balance calculation of the odd-mode frequency-divided steady-state solution.

Microwave transistor stability is a real preoccupation of MMICs designers. In this paper, it is shown that the classical electrical lumped model is inappropriate to the FET stability study. A non linear finger-distributed modeling technique, based on an electromagnetic deem bedding, is presented. The derived model exhibits a very interesting capability to predict the electrical behavior of arbitrary shaped transistor. It also brings a real improvement in the FET analysis study.

An electrothermal characterization of GaAs MESFET has been performed using pulsed measurements. The measurement process has been realized under the same bias conditions at different temperatures of the device. It allows the determination of a nonlinear model at each temperature Moreover the characterization method is based on the electrical measurement of the temperature channel. This specific measurement process under pulsed bias conditions allows to derive a full electrothermal nonlinear model representing the transistor self heating phenomena. The obtained values have been validated by a full three dimensional thermal simulation.

Stability analysis of MMICs becomes a preoccupation of engineers for the design of power amplifiers as well as of oscillators. In this paper it is shown that the classical approach of linear stability analysis fails in the case of unstable unloaded circuits. Nyquist based methods are proposed to circumvent this problem. A method relying on the general Harmonic Balance formulation is proposed, which enables the linear and non linear stability analysis. Examples of global stability analysis based on the resolution of the bifurcation equations are given. Finally an open loop method is proposed which allows to design analog frequency dividers with the aid of standard CAD packages.