Glucose Penetration Research Articles

An in vitro evaluation of two dentine adhesive systems to seal the pulp chamber using a glucose penetration model

To evaluate the sealing capability of Cavit™ G with or without Clearfil™ S3 Bond and Prime & Bond NT placed in the pulp chamber. Forty single rooted premolars, extracted for orthodontic and periodontal reasons, with intact coronal surface and mature apices, were standardized to a length of 15 mm. The teeth were instrumented, filled with a gutta-percha master cone and divided into three groups to obturate the pulp chambers: Cavit™ G; Clearfil™ S3 Bond plus Cavit™ G and Prime & Bond® NT plus Cavit™ G. A glucose leakage model was used for evaluating the coronal microleakage. The Mann-Whitney test was used to evaluate the differences in the means of the glucose leakage. An increase in glucose penetration was observed during the first week in groups Cavit™ G and Cavit™ G+PBNT. The glucose penetration values of all groups were similar at 30 and 45 days, and there were no significant differences among them in both time periods (p=0.736 and p=0.581, respectively). The adhesive systems did not improve the capability of Cavit™ G to seal the pulp chamber over time.

Intraorifice sealing ability of different materials in endodontically treated teeth

To evaluate Cavit TM G, ProRoot TM MTA and Tetric® EvoFlow as intraorifice barriers to prevent coronal microleakage in root canal treatment. Forty-two human single rooted teeth were divided randomly in three experimental groups of 10 specimens each and two control groups. The experimental groups were prepared with hand instrumentation and cold lateral condensed technique of the gutta-percha. Four millimetres of coronal gutta-percha were removed and replaced by one of the following filling materials: Cavit TM G, Tetric® EvoFlow or ProRoot TM MTA. In the experimental groups, leakage was measured by the concentration of leaked glucose in the apical reservoir at 1, 7, 30, and 45 days, using the enzymatic glucose oxidase method. Data were analyzed by means of Mann-Whitney U and Kruskal-Wallis tests at α=0.05. The glucose penetration results of three experimental groups increased gradually over time. No significant differences were found among groups at 24 hours and 1 week. At thirty and forty-five days, Cavit TM and Tetric® EvoFlow values were significantly different (p=0.007 and p=0.023, respectively). The sealing ability of the Cavit TM G, ProRoot TM MTA and Tetric® EvoFlow used as intraorifice materials tends to be similar over time.

Effect of moisture on sealing ability of root canal filling with different types of sealer through the glucose penetration model

Objectives: To compared the effect of different levels of moisture of root canal on the sealing ability after filling with four different types of sealer. Materials and Methods: Single-rooted teeth (n = 90) instrumented to and apical size of 0.06 / 45 were randomly assigned to 12 experimental groups (n = 7 per group), positive/negative control groups (n = 3 per group). The teeth of the experimental groups (a. DRY; b. PAPER POINT DRY; c. WET) were obturated with sealer (Group 1-3: Sealapex; Group 4-6: AH plus; Group 7-9: Tubuli-seal; Group 10-12: EndoRez) and warm vertical compaction method. After 7 days in , 100% humidity, the coronal-to-apical microleakage was evaluated quantitatively using a glucose leakage model. The leaked glucose concentration was measured with spectrophotometer at 1, 3, 7, 14, 21, and 30 days. Data were recorded ad mmol/L and statistically analysed with the two-way ANOVA and Duncan test (p = 0.05). Results: Throughout the experimental period Tubuli-seal/WET (Group 9) showed the highest mean cumulative glucose penetration (178.75 mmol/L), whereas AH plus/DRY (Group 4) had the least (20.78 mmol/L). Conclusions: The results of this study demonstrated that the moisture condition of root canals at the time of obturation and the type of sealer that was used had a significant effect on leakage and sealing ability. Thus drying procedure according to sealer types is a critical step and should not be missed in endodontic treatment.

Corono‐apical leakage of various root filling materials using two different penetration models—A 3‐month study

The purpose of this study was to analyze the sealing ability of various filling combinations in a 90 days period using fluid transport and glucose penetration models. Premolars (n = 108) were filled with either gutta-percha (groups 1-4) or Resilon (groups 5-8) core materials combined with AH Plus (groups 1, 3, 5, 7) or Epiphany (groups 2, 4, 6, 8) sealers by using cold lateral compaction (groups 1, 2, groups 5, 6) or System B with Obtura II (groups 3, 4, groups 7, 8). The sealing ability of each sample was evaluated through glucose and fluid penetration models. Penetration values of 90 days were statistically analyzed with three-way analysis of variance (ANOVA)and Duncan's Multiple Range tests (p < 0.05). No significant differences were found among the penetration values when the fluid filtration model was used (p > 0.05). On the contrary, statistically significant differences were obtained among the groups with the glucose penetration model (p < 0.05). AH Plus/Resilon/cold lateral compaction group had better sealing ability than the other combinations tested with the glucose penetration model.

Comparability of results from two leakage models

The goal of this study was to check whether leakage results of the same specimens measured by 2 different leakage models are similar. Canine root canals were prepared and filled with cold gutta-percha cones and 1 of 4 sealers (20 canals for each sealer). The 80 specimens were first connected to a fluid transport model where air-bubble movement was measured. The same specimens were later connected to a glucose penetration model where the concentration of glucose was measured. In both models, a headspace pressure of 30 kPa was used to accelerate leakage. In both models, 4 sealers ranked the same regarding the leakage they allowed, and a significant correlation between the results of the 2 models was confined (Spearman test coefficient = 0.65; P = .000001). Under the conditions of this study, leakage results of 80 specimens recorded in the fluid transport model and glucose penetration model were similar.

Sealing Ability of a New Polydimethylsiloxane-based Root Canal Filling Material

We tested the null hypothesis that there is no difference in the sealing ability of GuttaFlow, RoekoSeal, and AH26 in root canals. Sixty extracted mandibular premolars were filled with AH26 (lateral compaction), RoekoSeal, or GuttaFlow (modified single-cone). The sealing ability of the root canal fillings was measured weekly (4 weeks) by using a glucose penetration model. Kruskal-Wallis test revealed significant differences in glucose penetration between the experimental groups at weeks 1, 2, 3, and 4. Whereas GuttaFlow showed the highest amount of leakage at all times, AH26 showed the lowest. There was no significant difference between RoekoSeal-filled and AH26-filled root canals throughout the experimental period. AH26 showed better sealing ability in root canals than GuttaFlow.

Evaluation of the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals through the glucose penetration model

To compare the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals using a recently introduced glucose penetration model. Premolars (n = 156) instrumented to an apical size of .06/40 were divided into 12 experimental and 2 control groups. The root canals were filled with either gutta-percha (groups 1-6) or Resilon (groups 7-12) core materials combined with AH Plus (groups 1, 4, 7, 0), Ketac Endo (groups 1, 5, 8, 11), or Epiphany (groups 2, 6, 9, 12), using cold lateral compaction (groups 1-3, 7-9) or System B with Obtura II (groups 4-6, 10-12). The leaked glucose concentration was measured spectrophotometrically at 1, 8, 15, 22, and 30 days. Percentage leaking of each group was also calculated. Data were recorded as mmol/L and statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests (P = .05). Throughout the experimental period Resilon/Ketac-Endo/cold lateral compaction (group 8) showed the highest mean cumulative glucose penetration (mmol/L) (17.27 +/- 10.32), whereas Resilon/AH Plus/cold lateral compaction (group 7) had the least (3.36 +/- 4.65) (P < .05). At the 30(th) day, the least leaking percentage was observed in gutta-percha, Epiphany/cold lateral compaction (group 3). Glucose penetration was affected by the obturation technique in some groups. Ketac-Endo either with gutta-percha (group 2) or Resilon (group 8) indicated significantly less glucose penetration in warm technique, whereas gutta-percha/Epiphany (group 3) had significantly less glucose penetration in cold technique (P < .05). All material/technique combinations allowed glucose penetration. Gutta-percha/AH Plus combinations allowed similar patterns of glucose penetration to Resilon/Epiphany combinations.

Glucose penetration and fluid transport through coronal root structure and filled root canals

To measure glucose penetration and fluid transport through coronal root structure and compare it with leakage along the coronal region of root fillings. A total of 50 single-rooted teeth were selected and divided into three groups. Ten roots were sectioned longitudinally and the apical portion was removed leaving a total length of 9 mm. These 20 half-roots served as group 1: root structure (n = 20). The canals of the remaining 40 roots were prepared to size 50 and filled with vertically compacted injectable filling material and sealer. Group 2: Resilon + Epiphany (n = 20) and group 3: gutta-percha + AH26 (n = 20). The apical portion of the root was removed. Glucose penetration through the coronal root structure and coronal root fillings was checked over a period of 4 weeks and fluid transport was measured after completion of the glucose penetration test. Differences between the groups were statistically analysed with the Kruskal-Wallis test and the Mann-Whitney test. The three groups presented significantly different glucose penetration (P < 0.05). The two groups of filled canals showed significant glucose leakage whilst the root structure group did not show any leakage. In the fluid transport model, the root structure group also did not show any leakage. No significant difference in leakage existed between the two vertically compacted filling materials, Resilon with Epiphany sealer and gutta-percha with AH26 in both models (P > 0.05). Under the conditions of this study, in both models used, no leakage was observed through root structure. Filled canals were associated with penetration of glucose regardless of the material used.

An evaluation of the influence of passive ultrasonic irrigation on the seal of root canal fillings

To evaluate the influence of passive ultrasonic irrigation (PUI) on the seal of root canal fillings. A total of 40 mandibular premolars were distributed equally into two groups and the root canals were cleaned and shaped; they were then filled with gutta-percha and AH26 (sealer) using the warm vertical compaction technique with the System B (Analytic Technology, Redmond, WA, USA) device. In one group PUI was applied, after completion of instrumentation and hand-irrigation. In the other group, PUI was not applied. Thereafter, leakage of glucose was evaluated by measuring its concentration once a week for a total period of 56 days using a glucose penetration model. Differences between the groups in terms of glucose concentrations were statistically analysed with the Mann-Whitney test; the level of significance was set at P=0.05. After the first month the root fillings in teeth where PUI had been used, sealed the root canal significantly better than in teeth where no PUI had been used (P=0.017). Root fillings sealed the root canal better when PUI had been used.

Leakage along apical root fillings with and without smear layer using two different leakage models: a two‐month longitudinal ex vivo study

To compare two different experimental models when measuring leakage along root fillings with or without smear layer. One hundred and twenty single-rooted teeth were prepared to size 50 and allocated to two groups: fluid transport model (n = 60) and glucose penetration model (n = 60). The roots in each group were divided into three subgroups of 20 teeth each. Smear layer was left in place in group 1 but removed in groups 2 and 3. In groups 1 and 2 canals were filled with laterally compacted gutta-percha cones and AH 26. Group 3 was laterally compacted with Resilon cones and Epiphany sealer. The coronal portion of the filling was removed to assure only 4 mm of filling remained in the canal. Leakage of glucose was evaluated by measuring its concentration once a week for a total period of 56 days using a glucose penetration model. Fluid transport was evaluated by measuring the movement of an air-bubble using a fluid transport model, 1 and 8 weeks after canal filling. Differences between the groups in glucose concentrations and fluid transport were statistically analysed with the Kruskal-Wallis and the Mann-Whitney tests. The level of significance was set at alpha = 0.05. Glucose penetration was significantly different between the three groups after the first 8 days (P < 0.05). Resilon leaked the most throughout the experiment period. No significant difference (P > 0.05) existed between the two gutta-percha groups at all time intervals (Mann-Whitney test). In the fluid transportation model, no statistically significant differences were observed between all three experimental groups (P > 0.05) at either 1 or 8 weeks after filling (Kruskal-Wallis test). Under the conditions of this study, the glucose penetration model was more sensitive in detecting leakage along root fillings. Removing the smear layer before filling did not improve the sealing of the apical 4 mm of filling. Resilon allowed more glucose penetration but the same amount of fluid transport as the gutta-percha root fillings.

Glucose Diffusion in Pancreatic Islets of Langerhans

We investigate the time required for glucose to diffuse through an isolated pancreatic islet of Langerhans and reach an equilibrium. This question is relevant in the context of in vitro electrophysiological studies of the response of an islet to step changes in the bath glucose concentration. Islet cells are electrically coupled by gap junctions, so nonuniformities in islet glucose concentration may be reflected in the activity of cells on the islet periphery, where electrical recordings are made. Using a mathematical model of hindered glucose diffusion, we investigate the effects of the islet porosity and the permeability of a surrounding layer of acinar cells. A major factor in the determination of the equilibrium time is the transport of glucose into islet β-cells, which removes glucose from the interstitial spaces where diffusion occurs. This transport is incorporated by using a model of the GLUT-2 glucose transporter. We find that several minutes are required for the islet to equilibrate to a 10 mM change in bath glucose, a typical protocol in islet experiments. It is therefore likely that in electrophysiological islet experiments the glucose distribution is nonuniform for several minutes after a step change in bath glucose. The delay in glucose penetration to the inner portions of the islet may be a major contributing factor to the 1–2-min delay in islet electrical activity typically observed after bath application of a stimulatory concentration of glucose.

Impaired cerebral glucose metabolism in myotonic dystrophy: a triplet-size dependent phenomenon

Myotonic dystrophy (DM) is caused by an expansion of a CTG triplet repeat sequence in the 3′-noncoding region of a protein kinase gene, yet the mechanism by which the triplet repeat expansion causes disease remains unknown. Impaired glucose penetration into brain tissues has been described in DM patients and is a phenomenon that remains unexplained. The present study shows that altered brain glucose metabolism is triplet repeat dependent. We studied brain glucose metabolism (CMRGlu, μmol/100 g/min) by the use of positron emission tomography and 18F-fluoro-2-deoxy- d-glucose in 11 ambulatory non-obese DM patients and in 11 age and sex matched healthy subjects. All subjects underwent a glucose tolerance test with plasma insulin determinations. The expansion of CTG triplet repeats was analyzed in patients with the probe cDNA25 after EcoRI digestion. As compared to controls, in DM patients, the CMRGlu was significantly decreased (26.26±5.05 vs. 33.43±2.18, μmol/100 g/min, P=0.004), and after oral glucose loading, plasma insulin levels were significantly higher and plasma glucose levels remained unchanged (respectively, F=11.21, P=0.004 and F=0.20, P=0.66). Subsequently, the glucose/insulin ratio was significantly lower in DM patients ( F=6.25, P=0.02). The length of the expansion of the CTG repeats correlated negatively with the CMRGlu ( r 2=0.63, P=0.003) and positively with the area under the curve for insulin changes over time after oral glucose ( r 2=0.49, P=0.016). We conclude that, in DM patients, the brain metabolism of glucose is impaired in a repeat dependent manner.

The permeability of lysosomes to sugars. Effect of diethylstilbestrol on the osmotic activation of lysosomes induced by glucose.

We have investigated the effect on the osmotic activation of rat liver lysosomes, by glucose penetration, of different substances known to inhibit the glucose transport through the plasma membrane. Diethylstilbestrol is the most efficient, particularly when purified lysosomes are used. It has no effect on osmotic activation induced by hypo-osmotic sucrose or by iso-osmotic KCl. It is proposed that diethylstilbestrol reacts with specific sites involved in the glucose translocation through the lysosomal membrane. These sites could not be identified by binding experiments, presumably owing to the considerable unspecific binding of the compound to the membrane.

Limitation in glucose penetration from the liver into blood and other metabolic symptoms of ethanol withdrawal in rats

Studies were undertaken to determine whether the distribution of glycolytic intermediates between the blood and liver in rats would be changed upon ethanol consumption and after its withdrawal. More drastic impairment of energy metabolism appeared to occur after ethanol withdrawal than upon chronic ethanol ingestion. The major metabolic manifestations of withdrawal were severe hypoglycemia, hyperlactatemia and dramatic hypopyruvatemia. The liver/blood gradient of glucose attained a value of 4.2 after ethanol withdrawal, suggesting that glucose penetration from the liver into circulation became limited. Besides, glycogen was accumulated in the liver of withdrawn animals despite the severe hypoglycemia.

Pore properties of the Golgi membrane from lactating-rat mammary gland. Effects of pH and temperature and reconstitution into phospholipid vesicles.

Golgi-membrane vesicle penetration was studied by osmotic lysis. Pronounced temperature dependence of mannitol and mannoheptitol penetration over 0-37 degrees C gave linear Arrhenius plots, with activation energies of 75 and 117 kJ/mol respectively. Glucose penetration was constant over pH 5-9, but was respectively faster and slower at higher and lower pH values. Solubilized, dialysed, heat-stable extracts of Golgi membrane were reconstituted into egg yolk phospholipid membranes with apparent recovery of specific permeability. Penetration is interpreted in terms of a pore, for which the Renkin equation predicts a radius of about 0.54 nm.

Cholinergic synaptic vesicles isolated from Torpedo marmorata: Demonstration of acetylcholine and choline uptake in an in vitro system

The transport properties of highly purified synaptic vesicles, isolated from the purely cholinergic electric tissue of Torpedo marmorata, were studied in an in vitro system using column chromatography. Under iso-osmotic conditions, which did not result in substantial loss of endogenous acetylcholine or adenosine 5′-triphosphate, radiolabelled acetylcholine and choline were accumulated into vesicles (and were releasable by hypo-osmotic shock) by a time- and temperature-dependent process. Acetylcholine uptake was saturable with a K T for transport of 3.13mM; this was competitively inhibited by choline, with a K Tapp of 8.33 mM. Choline itself was also transported with a K T of 9.99mm. The facilitated uptake of both compounds was specifically inhibited by hemicholinium-3, but not the nonsaturable uptake seen at 0°C. Uptake of both compounds was inhibited by NaCl at concentrations above 2 mM. In double label experiments the rate of glucose penetration (identical with that of 2-deoxy- d-glucose) was found to be approximately 15–30-fold less than that of choline or acetylcholine. The accumulation of [ 14C]glucose remained linear at all concentrations used, at both 0°and 26°C. After 1 h incubation at 26°C the vesicular volume contained between 3 and 6 times the concentration of labelled acetylcholine and choline compared to that in the surrounding medium. The glucose concentration in the vesicles, however, remained well below that in the medium. Vesicles mechanically or chemically treated to release their soluble contents appeared to have a much reduced capacity to take up acetylcholine, and in most cases, choline also. These results demonstrate the existence in synaptic vesicles of a mechanism for the uptake and retention of acetylcholine (possibly against extremely high concentration gradients) which is not specific enough to exclude choline, at least as a pharmacological agonist in vitro.

Permanent neonatal diabetes mellitus: a case report with plasma insulin studies.

The 11th case of permanent neonatal diabetes mellitus appearing during the first month of life is reported. A critical review of the literature is also presented. The permanence of diabetes is demonstrated by the duration of insulin therapy still necessary after 30 months. Insulin-stimulation tests have been performed some for the first time in such a young diabetic. They have shown a nearly total failure in beta-cell response, only very high doses of glucagon provoking a moderate insulin secretion. The absence of acetonuria is discussed. It can perhaps be explained by the hyperglycemia which, by a mass effect, brings about cellular glucose penetration and this stops liberation of Nefa's from adipose tissue.

Effects of psychotropic drugs on the erythrocyte permeability to glucose and ethylidene glucose

The effect of chlorpromazine (CPZ) and a number of CNS depressant drugs on glucose penetration through human erythrocyte membrane has been investigated by an optical technique. CPZ accelerated glucose exit at concentrations between 1 × 10 −5 and 2 × 10 −5 M at 36° but at higher concentrations inhibited transfer. This inhibition was rapidly and completely reversible. CPZ, trifluoperazine, prochlorperazine, promazine and promethazine were found to inhibit glucose exit approximately in the order of their chemotherapeutic potency. Imipramine also showed this effect but nealbarbitone, thiopentone and haloperidol did not. CPZ affects the entry of glucose into erythrocytes in a biphasic manner similar to its effect on exit but at all concentrations it accelerates the penetration of ethylidene glucose which enters by diffusion. CPZ had no effect on the inhibition of glucose transfer produced by incubation with dinitrofluorobenzene (DNFB) or on the enhancement of this inhibition by incubation in the presence of glucose and 2-deoxyglucose. It is suggested that at low concentrations CPZ accelerates the movement of the glucose carrier within the membrane by effects on its charge environment. At higher concentrations interaction with the protein of both membrane and carrier presumably causes interference with carrier movement until at high concentrations haemolysis occurs. The relevance of these effects to the pharmacological action of CPZ is discussed.

Corneal glucose flux. II. Its response to anterior chamber blockade and endothelial damage.

The flux of glucose at the anterior stromal surface of the cornea is 575 nanomol/sq cm/hr in anesthetized rabbits. Blockade of the endothelial surface with air and silicone oil reduces the glucose flux to less than 20% of normal, reflecting the small amount of glucose which is available to the epithelium from the limbus. Blood in the anterior chamber reduces the flux to about 50% of normal. Interference with normal endothelial function by mechanical or thermal damage increases the movement of glucose across the cornea, which may indicate that the endothelium ordinarily acts as a relative permeability barrier to glucose penetration from the aqueous humor into the corneal stroma.

D(+)‐Glucose permeability in brown trout Salmo trutta L. erythrocytes

D(+)‐Glucose penetration in trout erythrocytes was studied with osmotic and tracer methods.Results give no evidence for a carrier mediated diffusion system like that concerned with glucose permeability as in human red cells. The data show that glucose fails to stimulate erythrocyte respiration.