Ultrasonic versus high-speed cavity preparation: Analysis of increases in pulpal temperature and time to complete preparation

Statement of problem. The use of ultrasonic tips has become an alternative for cavity preparation. However, there are concerns about this type of device, particularly with respect to intrapulpal temperatures and cavity preparation time.Purpose. The purpose of this study was to analyze pulpal temperature increases generated by an ultrasonic cavity preparation with chemical vapor deposition (CVD) tips, in comparison to preparation with a high-speed handpiece with a diamond rotary cutting instrument. The time required to complete the cavity preparation with each system was also evaluated.Material and methods. Thermocouples were positioned in the pulp chamber of 20 extracted human third molars. Slot-type cavities (3 x 3 x 2 mm) were prepared on the buccal and the lingual surfaces of each tooth. The test groups were: high-speed cavity preparation with diamond rotary cutting instruments (n = 20) and ultrasonic cavity preparation with CVD points (n = 20). During cavity preparation, the increases In pulpal temperature, and the time required for the preparation, were recorded and analyzed by Student's t test for paired samples (alpha = .05).Results. The average pulpal temperature increases were 4.3 degrees C for the high-speed preparation and 3.8 degrees C for the ultrasonic preparation, which were statistically similar (P = .052). However, significant differences were found (P < .001) for the time expended (3.3 minutes for the high-speed bur and 13.77 minutes for the ultrasound device).Conclusions. The intrapulpal temperatures produced during cavity preparation by ultrasonic tips versus high-speed bur preparation were similar. However, the use of the ultrasonic device required 4 times longer for the completion of a cavity preparation.

cAMP signaling pathway controls glycogen metabolism in Neurospora crassa by regulating the glycogen synthase gene expression and phosphorylation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Pulpal temperature increases with Er : YAG laser and high-speed handpieces

Statement of problem. During tooth preparation, both high-speed handpieces and lasers generate heat, which, if not controlled, can cause pulpal necrosis.Purpose. The aim of this study was to compare temperature increases produced by a high-speed dental handpiece with those produced by a relatively new instrument, the Er:YAG (erbium: yttrium-aluminum-garnet) laser.Material and methods. Thirty bovine mandibular incisors were reduced to an enamel/dentin thickness of 2.5 mm. Class V preparations were completed to a depth of 2.0 mm, measured with a caliper or by a mark oil the burs. A thermocouple was placed inside the pulp chamber to determine temperature increases (degreesC). Analysis was performed on the following groups (n = 10): Group 1, high-speed handpiece without water cooling, Group 11, high-speed handpiece with water cooling (30 mL/min), and Group III, the noncontact Er:YAG laser (2.94 mum at 350 mJ/10 Hz) with water cooling (4.5 mL/min). The temperature increases were recorded by a computer linked to the thermocouples. The data were analyzed using the Kruskal-Wallis test. The Dunn multiple comparison test was used as post hoc test (alpha = .05).Results. The average temperature rises were: 11.64degreesC (+/-4.35) for Group 1, 0.96degreesC (+/-0.71) for Group 11, and 2.69degreesC (+/-1.12) for Group III. There were no statistical differences between Groups 11 and III, both 11 and III differed from Group I significantly (P = .000 and P = .002, respectively).Conclusion. The preparations made with the high-speed and the laser instrument generated similar heat increases under water cooling. Water cooling was essential to avoid destructive temperature increases when using both the high-speed handpiece and laser.

Squalene does not exhibit a chemopreventive activity and increases plasma cholesterol in a Wistar rat hepatocarcinogenesis model

The eventual chemopreventive effect of squalene (SQ), a triterpene present in olive oil, was evaluated when administered to Wistar rats during a period comprising the initiation and selection/promotion of the resistant hepatocyte (RH) model of hepatocarcinogenesis. During 8 consecutive wk, animals received by gavage SQ (100 or 150 mg/100 g body weight) dissolved in corn oil (CO) daily. Animals treated with only CO and submitted to the RH model were used as controls. Treatments with SQ did not result in inhibition of macroscopically visible hepatocyte nodules (P > 0.05) or of hepatic placental glutathione S-transferase-positive preneoplastic lesions (PNL; P > 0.05). Hepatic cell proliferation and apoptosis indexes were not different (P > 0.05) among the different experimental groups, both regarding PNL and surrounding normal tissue areas. There were no significant differences (P > 0.05) among comets presented by rats treated with the two SQ doses or with CO. on the other hand, SQ increased total plasma cholesterol levels when administered at both doses (P < 0.05). This indicates that the isoprenoid was absorbed. Thus, SQ did not present chemopreventive activity during hepatocarcinogenesis and had a hypercholesterolemic effect, suggesting caution when considering its use in chemoprevention of cancer.

Granulocyte colony-stimulating factor expression from transduced vascular smooth muscle cells provides sustained neutrophil increases in rats

Granulocyte colony-stimulating factor (G-CSF) regulates granulocyte precursor cell proliferation, neutrophil survival, and activation. Cyclic hematopoiesis, a disease that occurs both in humans and grey collie dogs is characterized by cyclical variations in blood neutrophils. Although the underlying molecular defect is not known, long-term daily administration of recombinant G-CSF eliminates the severe recurrent neutropenia, indicating that expression of G-CSF by gene therapy would be beneficial. As a prelude to preclinical studies in affected collie dogs, we monitored hematopoiesis in rats receiving vascular smooth muscle cells transduced to express G-CSF. Cells transduced with LrGSN, a retrovirus expressing rat G-CSF, were implanted in the carotid artery and control animals received cells transduced with LASN, a retrovirus expressing human adenosine deaminase (ADA). Test animals showed significant increases in neutrophil counts for at least 7 weeks, with mean values of 3,670 +/- 740 cells/mu l in comparison to 1,870 +/- 460 cells/mu l in controls (p < 0.001). Thus, in rats G-CSF gene transfer targeted at vascular smooth muscle cells initiated sustained production of 1,800 neutrophils/mu l, a cell number that would provide clinical benefit to patients. Lymphocytes, red cells and platelets were not different between control and test animals (p > 0.05). These studies indicate that retrovirally transduced vascular smooth muscle cells can provide sustained clinically useful levels of neutrophils in vivo.

Thiobacillus ferrooxidans response to copper and other heavy metals: growth, protein synthesis and protein phosphorylation

Respirometric experiments demonstrated that the oxygen uptake by Thiobacillus ferrooxidans strain LR was not inhibited in the presence of 200 mM copper. Copper-treated and untreated cells from this T. ferrooxidans strain were used in growth experiments in the presence of cadmium, copper, nickel and zinc. Growth in the presence of copper was improved by the copper-treated cells. However, no growth was observed for these cells, within 190 h of culture, when cadmium, nickel and zinc were added to the media. Changes in the total protein synthesis pattern were detected by two-dimensional polyacrylamide gel electrophoresis for T. ferrooxidans LR cells grown in the presence of different heavy metals. Specific proteins were induced by copper (16, 28 and 42 kDa) and cadmium (66 kDa), whereas proteins that had their synthesis repressed were observed for all the heavy metals tested. Protein induction was also observed in the cytosolic and membrane fractions from T. ferrooxidans LR cells grown in the presence of copper. The level of protein phosphorylation was increased in the presence of this metal.

Human herpesvirus type 6 and type 1 infection increases susceptibility to nonmelanoma skin tumors

In order to investigate herpesvirus (HHV) role in the susceptibility to skin cancer, we compared HHV6 and HHV1 incidence in DNA samples extracted from 120 lesions and 41 normal skin tissues. HHV6 (31.7%) and HHV1 (23.8%) were detected more frequently in skin cancer than in control individuals (14.6 and 5%, respectively) (P=0.0391 and P=0.00094, respectively). The risk of presenting basal cell carcinomas (BCC) was more than 3 times higher for HHV-6 infected patients (OR=3.182; 95% CI: 1.125-8.997). The risk for HHV-1 infected individuals of presenting BCC and squamous cell carcinomas was increased 8 and 6 times, respectively (OR=8.125; 95% CI: 1.735-38.043 and OR=6.290; 95% CI: 1.283-30.856, respectively). (c) 2004 Elsevier B.V.. All rights reserved.

Glucose- and insulin-induced phosphorylation of the insulin receptor and its primary substrates IRS-1 and IRS-2 in rat pancreatic islets

The presence of tyrosine-phosphorylated proteins was studied in cultured rat pancreatic islets, Immunoblotting performed with total extracts of islets cultured in the presence of 1.8 or 5.6 mM glucose revealed at least three distinct tyrosine-phosphorylated bands (25 kDa, 95 kDa and 165-185 kDa). After 12 h incubation in medium containing 1.8 mM glucose, a pulse exposition to 11 or 22 mM glucose or to 10(-7) M insulin led to a substantial increase in the phosphorylation of all three bands, with no appearance of novel bands. Immunoprecipitation with specific antibodies demonstrated that the signal detected at 95 kDa corresponds to the beta subunit of the insulin receptor (IR) while the band at 165-185 kDa corresponds to the early substrates of the insulin receptor, IRS-1 and IRS-2. Immunoprecipitation with IRS-I or IRS-2 antisera detected their association with the lipid metabolizing enzyme phosphatidylinositol 3-kinase (PI 3-kinase), Thus, this is the first demonstration that elements involved in the insulin-signalling pathway of traditional target tissues are also present in pancreatic islets and are potentially involved in auto- and paracrine-signalling in this organ.

Protein deficiency during pregnancy and lactation impairs glucose-induced insulin secretion but increases the sensitivity to insulin in weaned rats

We studied glucose homeostasis in rat pups from darns fed on a normal-protein (170 g/kg) (NP) diet or a diet containing 60 g protein/kg (LP) during fetal life and the suckling period. At birth, total serum protein, serum albumin and serum insulin levels were similar in both groups. However, body weight and serum glucose levels in LP rats were lower than those in NP rats. At the end of the suckling period (28 d of age), total serum protein, serum albumin and serum insulin were significantly lower and the liver glycogen and serum free fatty acid levels were significantly higher in LP rats compared with NP rats. Although the fasting serum glucose level was similar in both groups, the area under the blood glucose concentration curve after a glucose load was higher for NP rats (859 (SEM 58) mmol/l per 120 min for NP rats v. 607 (SEM 52) mmol/l per 120 min for LP rats; P < 0.005). The mean post-glucose increase in insulin was higher for NP rats (30 (SEM 4.7) nmol/l per 120 min for NP rats v. 17 (SEM 3.9) nnol/l per 120 min for LP rats; P < 0.05). The glucose disappearance rate for NP rats(0.7 (SEM 0.1) %/min) was lower than that for LP rats (1.6 (SEM 0.2) %/min; P < 0.001). Insulin secretion from isolated islets (1 h incubation) in response to 16.7 mmol glucose/l was augmented 14-fold in NP rats but only 2.6-fold in LP rats compared with the respective basal secretion (2.8 mmol/l; P <0.001). These results indicate that in vivo as well as in vitro insulin secretion in pups from dams maintained on a LP diet is reduced. This defect may be counteracted by an increase in the sensitivity of target tissues to insulin.

Mechanism for the uncoupling of oxidative phosphorylation by juliprosopine on rat brain mitochondria

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synergistic action of both Aspergillus niger and Burkholderia cepacea in co-culture increases phosphate solubilization in growth medium

Co-inoculation of the fungus Aspergillus niger and the bacterium Burkholderia cepacia was undertaken to understand the interaction between different species of phosphate-solubilizing microorganisms (PSM). PSM were inoculated in a single or mixed (A. nigerB.similar to cepacia) culture. During 9 similar to days of incubation, microbial biomass was enhanced, accompanied with increases in the levels of soluble phosphate and titratable acidity, as well as increased acid phosphatase activity. Production of acids and levels of phosphate solubilization were greater in the co-culture of A.similar to nigerB.similar to cepacia than in the single culture. The quantity of phosphate solubilized by the co-culture ranged from 40.51 +/- 0.60 to 1103.64 +/- 1.21 similar to mu g similar to PO4 3-similar to mL-1 and was 922% higher than single cultures. pH of the medium dropped from 7.0 to 3.0 in the A.similar to niger culture, 3.1 in the co-culture, and 4.2 in the B.similar to cepacia culture. on the third day of postinoculation, acid production by the co-culture (mean 5.40 +/- 0.31 similar to mg NaOH mL-1) was 1990% greater than single cultures. Glucose concentration decreased almost completely (9799% of the starting concentration) by the ninth day of the incubation. These results show remarkable synergism by the co-culture in comparison with single cultures in the solubility of CaHPO4 under in vitro conditions. This synergy between microorganisms can be used in poor available phosphate soils to enhance phosphate solubilization.