Exponential tracking of general references and rejection of general disturbances for nonlinear control systems with applications to the blood glucose regulation system

In solving the problem of exponential tracking and disturbance rejection, it has been long always assumed that the reference to be tracked and the disturbance to be rejected are generated by an exosystem such as a finite dimensional system with pure imaginary eigenvalues. The aim of this note is to show that this assumption can be removed. For any nonlinear control system subject to a general disturbance, it can be split into a linear exponentially-stable system and a dynamical regulator system. If the dynamical regulator system has a solution, then there exists a feedback and feedforward controller such that an output of the control system exponentially tracks a desired general reference. The result is applied to the blood glucose regulation system.

Exponential tracking of general references and rejection of general disturbances for nonlinear control systems with applications to the blood glucose regulation system

In solving the problem of exponential tracking and disturbance rejection, it has been long always assumed that the reference to be tracked and the disturbance to be rejected are generated by an exosystem such as a finite dimensional system with pure imaginary eigenvalues. The aim of this note is to show that this assumption can be removed. For any nonlinear control system subject to a general disturbance, it can be split into a linear exponentially-stable system and a dynamical regulator system. If the dynamical regulator system has a solution, then there exists a feedback and feedforward controller such that an output of the control system exponentially tracks a desired general reference. The result is applied to the blood glucose regulation system.

Potential exploitation of Shea press cakes in glycaemia regulation: Inhibition of α-amylase and α-glucosidase by protein and methanolic extracts

Shea (Vitellaria paradoxa) tree is integrally used in traditional medicine for the treatment of several health disturbances. Its kernels fat is widely exploited for food, medicinal and cosmetic purposes. Nevertheless germinated kernels are considered as waste, whereas shea germinative power would be very high. Their anti-diabetic ability was evaluated in vitro, in ordre to highlight their pharmacological benefits. Therefore, both proteins (crude, digested and dialysed ones) and hydroalcoholic extracts, were prepared from germinated and ungerminated shea seed press cakes. The anti-diabetic essay was carried out by evaluating extracts inhibiting power on both α-amylase and α-glucosidase activities. Proteins were quantified by spectrophotometry (214 nm). Results revealed that the protein content of the extracts from germinated seed cakes was 450 mg/100 g and that of the extracts from ungerminated shea seed cakes was 410 mg/100 g. The percentage of inhibition of α-amylase by the dialysed extracts of germinated shea seeds, in this case the external dialysate of germinated seed, presented the best rate of inhibition with 30.21 %. Contrary to the percentage of inhibition of α-amylase, the highest rates of inhibition of α-glucosidase were recorded with the crude protein extracts of sprouted seeds (82.02 %) and unsprouted seeds (62.32 %). For methanolic extracts, the highest inhibition of α-amylase and α-glucosidase was recorded by the ungerminated seeds, with 42.61% for α-amylase and 97.47% for α-glucosidase. These results show that protein extracts of shea seed cakes may play a role in blood glucose regulation.

The Influence of Diet Change and Oral Metformin on Blood Glucose Regulation and the Fecal Microbiota of Healthy Horses

Common treatments for Equine Metabolic Syndrome (EMS) and associated conditions include removal from pasture and adoption of an all-hay diet. Pharmacological treatments for EMS include metformin, a biguanide antihyperglycemic agent also administered to people to help improve glucose tolerance and insulin sensitivity. Both treatments may work, at least partially, through the gut microbiota, yet little is known regarding these effects in the equine host. To determine the influence on the fecal microbiota of this diet change and administration of metformin, six healthy horses were removed from pasture and switched to an all-hay diet, with four of those horses also receiving oral metformin for seven days. Control horses (n = 24) remaining on pasture and receiving no metformin were sampled at the beginning and end of one week. All samples were subjected to 16S rRNA sequencing, and horses undergoing the diet change were subjected to an oral sugar test twice, one week apart. Characteristic changes in the microbiota following diet change included the significant expansion of the phylum Kiritimatiellaeota. As Kiritimatiellaeota are related to Verrucomicrobia, found to expand in the microbiota of mice and humans in response to metformin, this taxon may represent the cognate microbes in equine hosts.