Glucose possible mechanism

The significance of pH is particularly interesting since pH may either augment or diminish NH3 production. The possible mechanisms by which pH affects NH3 production are (a) inhibition of bacterial metabolism, (b) pH-dependent changes in urea metabolic pathways, (c) pH-dependent bacterial utilization of glucose and urea as energy sources, and (d) increased bacterial uti-... 

Figure 13.27 A possible mechanism by which a low blood glucose level could give rise to central fatigue. A low blood glucose level reduces the rate of glucose utilisation in the brain which decreases the ATP/ADP concentration ratio in the presunaptic neurone. This reduces the energy available for synthesis of neurotransmitters, packaging of neurotransmitter molecules into vesicles and exocytosis of neurotransmitter into synaptic cleft. This decreases electrical activity in postsynaptic neurones and hence in the motor pathway.

More direct interference with glucose metabolism cannot be excluded. Interferon alfa can reduce the sensitivity of peripheral tissues or liver to insulin and accelerate the destruction of stimulated pancreatic beta-cells (540,541) this could be a possible mechanism in patients not exhibiting islet cell antibodies. This is also in keeping with rare instances of induction or exacerbation of type II noninsulin dependent diabetes mellitus (SEDA-19, 335). 

The fits in this case are not as good as the ones obtained for the penicillin case (Figs. 2.10 and 2.11). This is due to the fact that the glucose oxidation mechanism is not yet completely understood and the kinetic equations are only approximate. Nevertheless, it is again possible to plot the profiles of the most important species in the gel layer and from this fit to estimate the optimum thickness of the gel layer (Fig. 2.17). For the glucose sensor, the optimum thickness appears to be 150pm,... 

There are some reports on possible mechanisms behind these effects of severe heat treatment. Adrian (1) has shown that water-soluble premelanoidins from a glucose-glycine reaction mixture reduce the protein digestibility and affect the utilization of... 

Saponins appear to lower plasma LDL cholesterol concentration by interfering with cholesterol absorption. Studies in rats and monkeys fed naturally occurring saponins exhibited significant reductions in cholesterol absorption efficiency and an increase in fecal cholesterol excretion (Malinow et al., 1981 Nakamura et al., 1999 Sidhu et al., 1987). Decreased bile acid absorption and increased excretion has also been reported in animals fed saponins (Malinow et al., 1981 Nakamura et al., 1999 Stark and Madar, 1993). One possible mechanism of action for decreased cholesterol absorption is the ability of saponins to form insoluble complexes with cholesterol (Gestetner et al., 1972 Malinow et al., 1977). In an effort to isolate the specific properties of saponins, Malinow (1985) prepared a variety of synthetic saponins in which the complex carbohydrate moieties of native plant saponins were replaced with simplified carbohydrates such as glucose or cellobiose. One of these synthetic saponins, tiqueside (Pfizer, Inc.), can effectively precipitate cholesterol from micelle solutions in vitro and inhibit cholesterol absorption in a variety of animals (Harwood et al., 1993) and in humans (Harris et al., 1997). But despite ample data showing the formation of a saponin/cholesterol complex in vitro, there is essentially no definitive evidence that complexation occurs in the intestinal lumen (Morehouse et al., 1999). 

Miglitol (73) is the most potent in a series of derivatives of the natural product moranoline (1-deoxynojirimycin) (72), which appear to closely mimic glucose (71), and which inhibit a-glucoamylase and sucrase [334]. Unlike acarbose, miglitol is almost completely absorbed, possibly via the glucose transporter mechanism, and is excreted through the kidney, a... 

A third possible mechanism involves a transfer of phosphate from MgATP to the enzyme, followed by release of MgADP before the glucose hinds and picks up the phosphate Fig. 4-46). This type of mechanism is called Ping Pong because the enzyme oscillates between two stable forms, and F. The reaction sequence is ... 

The effects of olanzapine on glucose-insulin homeostasis have been studied in 14 patients in an attempt to elucidate the possible mechanisms of olanzapine-associated weight gain (121). Olanzapine caused weight gain of 1-10 kg in... 

Maekawa F, Toyoda Y, Torii N, Miwa I, Thompson RC, et al. 2000. Localization of glucokinase-like immunoreactivity in the rat lower brain stem For possible location of brain glucose-sensing mechanisms. Endocrinology 141 375-384. 

The data given also clarify the possible mechanism of the formation of 2-deoxy-D-arabino-hexitoP and 1-deoxy-D-mannitoP in the preparative electrolysis of n-glucose in an alkaline medium. 

Modification of human serum albumin by o-glucose impaired its antiapoptotic activity for endothelial cells a 50% loss of activity corresponded to about four fiuctosamine residues per protein molecule. In another study, D-fiuctose-albumin enhanced nitric oxide synthase activity and a consequent NO-dependent apoptosis in vascular endothelial cells. " This effect was also attributed to a possible mechanism of hyperglycemia-induced vasculopathy in diabetic patients. In proximal tubular epithelial cells, however, the effect of co-incubated D-fiuctose-albumin was the... 

There have been strong arguments over the mechanism of peptide hydrolysis by carboxypeptidase. One possible mechanism is the anhydride mechanism [54] in which the oxygen of a carbonyl group is coordinated to a Zn ion, activation of an amide takes place, nucleophilic attack of -COO" of the glucose residue of the protein occurs to form an acid anhydride, and then the anhydride reacts with water by being activated by the Zn to result in hydrolysis (Fig. 2-30). 

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