Enzymatic Microdetermination of Glucose in Blood and Urine

Simultaneous Content Determination of Mono-, Di-, and Fructo-oligosaccharides in Citrus Fruit Juices Using an FTIR-PLS Method Based on Selected Absorption Bands

A quantification method was developed to determine the sugar components, either following addition or enzymatic treatment, in citrus fruit juices containing additional fructo-oligosaccharides using midinfrared spectroscopy. For the quantification, we compared the results obtained by applying the simultaneous equation method, which uses very little wavenumber information, and the partial least squares (PLS) regression method, which requires a lot of wavenumber information. In order to prevent overfitting in the PLS method, we concentrated on reducing the amount of spectral data used in the analysis. The corresponding FTIR-PLS method led to an accurate quantification of the sugar contents, even in enzymatically treated orange juices with complicated compositions. The spectral data used for model calibration were significantly reduced by focusing on the absorption and assignment information of the sugar components. The RMSEs of Glc, Fru, Suc, GF2, and GF3 in enzyme-treated orange juice before and after spectral data reduction were 0.50, 0.46, 0.61, 0.74, and 0.61 g/L and 0.51, 0.49, 0.73, 0.86, and 0.61 g/L, respectively. The developed method could be easily implemented for practical applications, using a simple measuring instrument since only absorption information at the limited absorption bands is required.

An ultra sensitive saccharides detection assay using carboxyl functionalized chitosan containing : nanoparticlesprobe

A novel saccharides detection assay based on covalent immobilization of amino phenyl boronic acid (APBA) in thin films of carboxyl functionalized chitosan (HOOC-chitosan) containing <5 nm Gd2O3 : Eu3+ nanoparticles at a platinum disc electrode was developed. The resulting HOOC-chitosan/Gd2O3 : Eu3+ nanocomposite film exhibited excellent electrochemical response to changes in the pKa values of boronate esters yielded from different vicinal diols of sugars. The covalent interaction of APBA onto the HOOC-chitosan/Gd2O3 : Eu3+ Pt-disc electrode was characterized with FT-IR, SEM, contact angle and cyclic voltammetry, whereas Gd2O3 : Eu3+ nanoparticles and HOOC-chitosan/Gd2O3 : Eu3+ nanocomposite was identified using XRD, EDX and TEM. A wide linear response was measured to boronate esters ranging from 25 nM to 13.5 μM (r2 = 0.963) with good reproducibility. The excellent electrochemical activity of the assay might be attributed to the synergistic effects of the balanced de-/protonated HOOC-chitosan, APBA and Gd2O3 : Eu3+ nanoparticles. With APBA as a model, the HOOC-chitosan/Gd2O3 : Eu3+ nanocomposite-modified Pt-electrode was constructed through a simple drop coating method. The resulting assay exhibited a good potentiometric response to different saccharides including glucose, and could be a promising application for the precise electrochemical detection of vicinal diols of specific sugars for clinical diagnostics, medicine validation, bioscience research and food analysis.

Responses of maxillary sensilla styloconica inBombyx mori to glucosides fromOsmunda japonica, a nonhost plant

We isolated glucosides from the royal fern,Osmunda japonica, which elicit a deterrent response in larvae ofBombyx mori. These compounds were absent in taro (Colocasia antiquorum) and castor-oil plant (Ricinus communis) leaves and did not evoke responses of sensory cells in the lateral and medial sensilla styloconica ofSpodoptera litura. This glucoside extract of the royal fern leaves stimulates receptors generally associated with deterrent. It is also possible that this compound may act as a behavioral deterrent, and from actual feeding tests, it is suggested that this compound may prevent feeding in some monophagous insects, such asBombyx mori. The deterrent glucoside possesses a noncyclic aglycon.

Hepatic portal injection of glucose elevates efferent sympathetic discharges of interscapular brown adipose tissue

Efferent sympathetic discharges of interscapular brown adipose tissue were recorded after three different concentrations of glucose (138, 277, and 416 mM) and 154 mM NaCl were injected into the portal vein or into the right jugular vein. When injected into the portal vein there was a significant increase in the discharge in response to both concentrations of glucose (277 and 416 mM), whereas only 416 mM glucose solution could cause an increase in the discharge when injected into the right jugular vein. There was no appreciable change in the discharge following the NaCl injections into the portal and jugular veins, and the portal glucose responses in the discharge were abolished by transection of the hepatic branch of the vagus nerve. Since stimulated sympathetic activity has been shown to elevate thermogenesis of the adipose tissue, these findings suggest that vagal glucose signals derived from the portal vein may be involved in the regulation of heat production of this tissue.

The effect of intrahypothalamic injections of glucose on sympathetic efferent firing rate

Electrical stimulation of the ventromedial hypothalamus of anesthetized rats, produced an increase in temperature of brown adipose tissue. The magnitude of increase in temperature was linearly related to the frequency (Hz) of electrical stimulation of the hypothalamus. Microinjection of glucose into the ventromedial hypothalamus produced a dose-dependent increase in firing rate of the sympathetic nerves to brown adipose tissue, whereas comparable volumes of physiological saline had no effect. Destruction of neurons in the ventromedial hypothalamus with injections of kainic acid completely blocked the stimulatory effect of glucose on the firing rate of nerves to the brown adipose tissue. These studies support the hypothesis that glucose sensitive neurons in the ventromedial hypothalamus can directly modulate sympathetic nerves supplying brown adipose tissue.

D-glucose anomers in the nucleus of the tractus solitarius can reduce gastric acid secretion of rats

The infusion of alpha-, beta-, or equilibrated (alpha:36%, beta:64%) D-glucose solution in or in the vicinity of the nucleus of the tractus solitarius decreased gastric acid output caused by insulin in rats with bilateral adrenalectomy. This effect was not reproduced after vagotomy at the cervical level. Of the three forms of D-glucose solution, the effect of beta-D-glucose was greatest. The infusion of equitonic NaCl, however, produced no change in the acid output. These results suggest that blood beta-D-glucose may predominantly activate a brain mechanism which through the vagus nerve modulates gastric acid secretion at the medullary level.

Alterations in gastric acid secretion following hepatic vagotomy at a stage of development in rats

The relation of gastric acid secretion to the hepatic vagal section was examined in consideration of developmental stages of a rat. Acid outputs in rats deprived of food for 22 hr before the experiment were estimated with or without insulin. The animals were classified into five groups according to their body weights at the experiments (50, 100, 200, 300 and 400 g). Hepatic vagotomy was effective in decreasing acid output in all of the groups treated with food deprivation and insulin, and it was found that there was a close relationship between the output and glucose concentration in the portal blood. In rats treated only with food deprivation, hepatic vagotomy produced different effects for the five groups; the vagotomy failed to cause acid response when the rats weighed about 300 and 400 g, while in the animals weighing about 50, 100 and 200 g acid outputs were reduced following the vagotomy. It was noted that the sensitivity to hypoglycemia in the acid output was greater in the young rats than the older ones. Results suggest that function of the hepatic vagal nerve may be prominent in modulating acid secretion in an earlier stage of development when the animals are most sensitive to hypoglycemia.

Effects of D-glucose anomers on sweetness taste and insulin release in man

Insulin release was examined in human subjects after lingual applications of D-glucose and its anomers. A dose-dependent increase in the insulin release was noted following the application of equilibrated D-glucose consisting of 36% alpha- and 64% beta-anomer. The response was not reproduced after administration of atropine. The magnitude of insulin release produced by alpha-anomer was different from that induced by beta-anomer in men who could not differentiate between sweetness of the two anomers. Results indicate that recognition of sweetness in the cortex is unrelated to the insulin response, and suggest that a subcortical mechanism may detect qualitative differences in taste and produce the oral phase of insulin secretion via vagus action in humans.

Inhibition of gastric motility induced by activation of the hypothalamic paraventricular nucleus

Electrical stimulation of the paraventricular nucleus depressed the intragastric pressure of adrenalectomized male rats of which gastric movement had been induced by insulin-hypoglycemia. Electrical stimulation to the pituitary stalk produced a similar response in the pressure, but the response was abolished by bilateral lesion of the paraventricular nucleus. These findings allow us to speculate that the paraventricular nucleus is capable of modulating gastric motility, and suggest that the nucleus has a neural connection between the neurohypophysis and the system relevant to visceral function.

Effects of D-glucose anomers on sweetness, taste and gastric acid secretion in man

Gastric acid outputs were examined in human subjects after lingual applications of d-glucose and its anomers. A dose-dependent increase in the acid output was noted following the application of equilibrated D-glucose consisting of 36% alpha- and 64% beta-anomer. The response was not reproduced after administration of atropin. The magnitude of acid output produced by alpha-anomer was different from that induced by beta-anomer in men who could not differentiate between sweetness of the two anomers. Results indicate that recognition of sweetness in the cortex is unrelated to the gastric response, and suggest that a subcortical mechanism may detect qualitative differences in taste and produce the oral phase of gastric acid secretion via vagus action in humans.

Different effects of D-glucose anomers on enhanced secretion of gastric acid in rat

The injection of alpha-, beta-, or equilibrated (alpha: 36%, beta: 64%) D-glucose solution into the cranial side of the carotid artery decreased gastric acid output caused by insulin in rats with bilateral adrenalectomy. This effect was not reproduced after vagotomy at the cervical level. Of the 3 forms of D-glucose solution the effect of beta-D-glucose was greatest. The injection of isotonic NaCl solution, however, produced no change in acid output. These results suggest that blood beta-D-glucose may play a predominant role in activating a brain mechanism which controls gastric acid secretion via the vagus nerve.

Inhibition of gastric acid secretion elicited by D-glucose anomers in man

Acid outputs from the stomach were measured after venous administration of D-glucose and its optical anomers in men with insulin hypoglycemia. A significant decrease in gastric acid output was noted after the administration of 277 mM alpha-D-glucose, 277 mM optically equilibrated D-glucose consisting of 36% alpha-anomer and 64% beta-anomer, or 277 mM beta-D-glucose. The effect of beta-D-glucose was most potent in the three forms of D-glucose. NaCl solution, however, produced no appreciable change in the acid outputs. Our findings suggested that, in humans, beta-D-glucose in the blood may play an important role in the activation of glucose-sensitive mechanisms controlling vagally mediated secretion of gastric acid.

Alterations in gastric acid secretion following hepatic portal injections of D-glucose and its anomers

Changes in acid outputs from the stomach were examined after portal injections of D-glucose and its optical anomers in the bilaterally adrenalectomized rats with insulin hypoglycaemia. Significant decrease in gastric acid outputs was noted after portal injections of alpha-D-glucose, optically equilibrated D-glucose (OEDG) consisting of 36% alpha-anomer and 64% beta-anomer and beta-D-glucose. The effect of beta-D-glucose was most potent in reducing the acid outputs and the inhibitory response was entirely prevented by prior vagotomy at the hepatic level. The injections of isotonic NaCl solution, however, produced no change in the acid outputs. Results suggest that changes in glucose levels in the portal vein may modulate gastric acid secretion through hepatic vagal afferents and gastric vagal efferents and suggest that activation of hepatic glucosensitive mechanisms may be dependent on the anomeric stereospecificity of D-glucose in the blood.

Glucose metabolism and dehydrogenase activities in the cytosol and mitochondria of mouse LS cells in chemostat culture

Energy metabolism has been examined in mouse LS cells growing under steady-state conditions in chemostat culture. The metabolic quotient of glucose oxidized (glucose consumed, but not fermented) remained constant, independent of growth rate between cell doubling times of 6 days and 1.2 days. Specific activities of cytochrome oxidase and malate dehydrogenase in the mitochondria remained constant at different growth rates, in accord with the constancy of the glucose oxidation rate. Cytosolic malate dehydrogenase activity was about fourfold greater than the mitochondrial isozyme. The steady-state rate of lactate production fluctuated because of technical limitations but correlated well with cytosolic lactate dehydrogenase activity.

Enzyme immobilization by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperatures

Enzyme immobilization by radiation-induced polymerization of hydrophilic glass-forming monomers, such as 2-hydroxyethyl methacrylate, was studied. Enzyme radiation damage could be sufficiently retarded at low temperatures. The immobilized enzyme activity yield was markedly higher at low temperature than at higher temperature polymerization. At low temperatures the polymerized composite had a porous structure owing to ice crystallization which depends on the monomer concentration. It was deduced that the enzyme was partially trapped on the polymer surface, partially isolated in the pore, and partially occluded inside the polymer matrix. A decrease in activity caused by enzyme leakage was observed with repeated use in enzyme reactions where the composites had a large porosity. The activity yield showed a maximum at certain optimum porosities, i.e., at optimum monomer concentrations. Continuous enzyme reaction was preferably carried out using immobilized enzyme columns.

Metabolic effects of constant hypertonic glucose infusion in well-oxygenated fetuses

In order to investigate the metabolic effects of a constant hypertonic glucose infusion in well-oxygenated fetuses, ten experiments were carried out in nine long-term experiments in fetal lambs. It appeared that a constant hypertonic glucose infusion did not significantly affect the fetal blood gases, pH, and plasma lactate levels when fetal glucose was kept below 150 mg. per 100 ml. It was also demonstrated that glucose infusions significantly increased the fetal lactate levels and decreased the blood pH when fetal plasma glucose was over 150 mg. per 100 ml. However, there was no decrease in fetal PO2 and pco2 until fetal glucose reached values over 300 mg. per 100 ml. These studies suggest that constant hypertonic glucose infusion does not improve fetal blood gases or pH and that fetal hyperglycemia over 300 mg. per 100 ml. produces severe metabolic acidosis.

Haemorrhagic diathesis as a possible early sign of hereditary fructose intolerance

An infant girl three weeks of age with the leading symptom of skin haemorrhages is presented. On further investigation, the signs of severe hepatic damage with hypofibrinogenaemia and prothrombin complex impairment, and renal tubular dysfunction were disclosed. All these pathological symptoms, which were reversed on fructose free diet, were caused by hereditary fructose intolerance.

Metabolism of maltose during surgery in patients with diabetes mellitus under general anesthesia

During a surgical operation under general anesthesia, maltose was administered at a rate of 1g/kg BW to 9 diabetic and 18 non-diabetic patients. The disappearance curve of maltose from blood was similar between diabetics and non-diabetics. Blood sugar tended to rise but no significant difference was found between the two groups. Lactic acid and pyruvic acid showed a tendency toward a rise, but the change was non-significant. NEFA and uric acid failed to change. Urinary excretion of maltose was not different between diabetics and non-diabetics. After 120 min., urinary excretion of maltose was similar between the two groups, but excretion as glucose was greater in the diabetic group.

Glucuronic acid pathway in alloxan diabetic rabbits. (I). Urinary excretion of metabolites related to the glucuronic acid pathway

Studies on the activity of the glucuronic acid pathway in alloxan diabetic rabbits were carried out. Amount of D-glucaric acid, L-ascorbic acid, and D-glucuronic acid in urine increased in the case of the alloxan diabetic rabbits. The transformation from D-glucuronolactone to D-glucaric acid was higher than normal in the diabetic animals. The expired 14-CO2 decreased and urinary excretion of labeled L-gulonic acid increased after administration of 6-14-C-glucuronolactone in the diabetic rabbits. L-Gulonic acid dehydrogenase, lactonase II, and beta-glucuronidase activities were reduced, and UDPGA-pyrophosphatase, D-glucuronic acid-1-phosphatase, and UDPGA-transferase activities increased in the diabetic rabbit liver. From these results, it may be concluded that an increase of endogenous D-glucuronic acid in the diabetic states could be attributed to a metabolid defect in the step of L-gulonic acid dehydrogenation and to the enhancement of UDPGA-pyrophosphatase and D-glucuronic acid-1-phosphate phosphatase activities.

Phospholipids of Streptococcus faecalis

Autoradiograms of total lipid extracts from Streptococcus faecalis ATCC 9790, harvested in the stationary phase from a medium containing (32)P-orthophosphate, showed six major spots. The corresponding compounds were identified as diphosphatidylglycerol (possibly with a penta acyl structure); phosphatidylglycerol; a provisionally identified mixture of alanylphosphatidylglycerol and of the 2'-lysyl-derivative of phosphatidylglycerol; the 3'-lysyl-derivative of phosphatidylglycerol, probably together with some arginylphosphatidylglycerol; a diglucosyl derivative of phosphatidylglycerol; and a compound which was tentatively identified as the 2',3'-dilysyl derivative of phosphatidylglycerol.