Ultrasonic Chemical Vapor Deposition-coated Tip versus High- and Low-speed Carbide Burs for Apicoectomy: Time Required for Resection and Scanning Electron Microscopy Analysis of the Root-end Surfaces

This study compared ultrasonic chemical vapor deposition (CVD)-coated tip (CVDentus #8.1117-1; Clorovale Diamantes Ind. e Com. Ltda Epp, Sao Jose dos Campos, SP, Brazil) versus high-speed (#FG700L) and low-speed (#699) carbide burs for apicoectomy, evaluating the time required for resection and analyzing the root-end surfaces by scanning electron microscopy. Thirty extracted human premolars had the canals instrumented and obturated and were randomly assigned to 3 groups (n = 10), according to the instrument used for root-end resection. The time required for resection of the apical 2 mm of each root was recorded. The resected apical segments were dried, sputter coated with gold, and examined with a scanning electron microscope at X 350 magnification. A four-point (0-3) scoring system was used to evaluate the apical surface smoothness. The results were analyzed statistically by the Kruskal-Wallis test and two-by-two comparisons analyses were performed using the Miller test. The significance level was set at 5%. Root-end resection with the high-speed bur was significantly faster (p < 0.05) compared with the low-speed bur and CVD tip. The carbide burs produced significantly smoother root-end surfaces than the CVD tip (p < 0.05). The low-speed bur produced the smoothest root-end surfaces, whereas the roughest and most irregular root ends (p < 0.05) were obtained with the CVD tip. However, no statistically significant difference (p > 0.05) was found between the high- and low-speed burs regarding the surface roughness of the resected root ends (p > 0.05). In conclusion, under the tested conditions, ultrasonic root-end resection took a longer time and resulted in rougher surfaces compared with the use of carbide burs at both high and low speed. (J Endod 2009;35:265-268)

Silicone implant for chin augmentation mimicking a low-grade liposarcoma

The silicone implant has been widely used in facial aesthetic surgery for chin augmentation. A case of a 71-year-old woman with a lesion in the anterior mandibular region detected by radiographies and suggestive of benign soft tissue tumor is presented. The patient denied previous surgical intervention in the mental area. A biopsy was performed and initially interpreted as low-grade liposarcoma. After an immunohistochemistry study showing CD-68-positive cells and complementary information regarding a silicone implant for chin augmentation, the definitive diagnosis was silicone granuloma. This case reinforces that silicone implant in the mandibular region can be misdiagnosed as malignant tumor and the correct diagnosis is heavily dependent on close collaboration between clinician and pathologist in order to avoid unnecessary surgical intervention. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107: e21-e23)

Methylation of O-6-methylguanine DNA methyltransferase characterizes a subset of colorectal cancer with low-level DNA microsatellite instability

The significance of low-level DNA microsatellite instability (MSI-L) is not well understood. K-ras mutation is associated with MSI-L colorectal cancer and with the silencing of the DNA repair gene O-6-methylguanine DNA methyltransferase (MGMT) by methylation of its promoter region. MGMT methylation was studied in sporadic colorectal cancers stratified as DNA microsatellite instability-high (n = 23), MSI-L (n = 44), and microsatellite-stable (n = 23). Methylation-specific PCR was used to detect MGMT-promoter hypermethylation in 3 of 23 (13%) microsatellite instability-high, in 28 of 44 (64%) MSI-L, and in 6 of 23 (26%) microsatellite-stable cancers (P = 0.0001). K-ras was mutated in 20 of 29 (69%) methylated MSI-L cancers and in 2 of 15 (13%) unmethylated MSI-L cancers (P = 0.001), indicating a relationship between MGMT-methylation and mutation of K-ras. Loss of nuclear expression of MGMT was demonstrated immunohistochemically in 23 of 31 (74%) cancers with methylated MGMT and in 10 of 49 (20%) cancers with nonmethylated MGMT (P < 0.0001). Loss of expression of MGMT was also demonstrated in 9 of 31 serrated polyps. Silencing of MGMT may predispose to mutation by overwhelming the DNA mismatch repair system and occurs with greatest frequency in MSI-L colorectal cancers.

High frequency of low-level microsatellite instability in early colorectal cancer

Molecular events in early colorectal cancers (CRCs) have not been well elucidated because of the low incidence of early CRCs in clinical practice. Therefore, we studied 104 sporadic early CRCs with invasion limited to submucosa compared with 116 advanced CRCs. Loss of heterozygosity as well as microsatellite instability (MSI) status was examined. A significantly high frequency of low-level MSI (MSI-L) phenotype was detected in early CRCs (51.0%) compared with advanced CRCs (25.9%; P = 0.0001). In early and advanced CRCs, samples with MSI-L phenotype differed from microsatellite stable (MSS) phenotype with respect to loss of heterozygosity at 1p32 and 8p12-22. MSI-L is a frequent genetic event in early CRCs and may be a novel pathway in colorectal carcinogenesis distinct from both MSI-H and MSS.

Eag1 potassium channel immunohistochemistry in the CNS of adult rat and selected regions of human brain

Eag1 (K(v)10.1) is the founding member of an evolutionarily conserved superfamily of voltage-gated K+ channels. In rats and humans Eag1 is preferentially expressed in adult brain but its regional distribution has only been studied at mRNA level and only in the rat at high resolution. The main aim of the present study is to describe the distribution of Eag1 protein in adult rat brain in comparison to selected regions of the human adult brain. The distribution of Eag1 protein was assessed using alkaline-phosphatase based immunohistochemistry. Eag1 immunoreactivity was widespread, although selective, throughout rat brain, especially noticeable in the perinuclear space of cells and proximal regions of the extensions, both in rat and human brain. To relate the results to the relative abundance of Eag1 transcripts in different regions of rat brain a reverse-transcription coupled to quantitative polymerase chain reaction (real time PCR) was performed. This real time PCR analysis showed high Eag1 expression in the olfactory bulb, cerebral cortex, hippocampus, hypothalamus, and cerebellum. The results indicate that Eag1 protein expression greatly overlaps with mRNA distribution in rats and humans. The physiological relevance of potassium channels in the different regions expressing Eag1 protein is discussed. (C) 2008 IBRO. Published by Elsevier Ltd. All rights reserved.

Low Level Laser Effects On Pain to Palpation and Electromyographic Activity in TMD Patients: A Double-Blind, Randomized, Placebo-Controlled Study

The purpose of this study was to evaluate the effect of diode laser (GaAlAs - 780 nm) on pain to palpation and electromyographic (EMG) activity of the masseter and anterior temporalis muscles. The laser was applied on the temporalis and masseter muscles twice a week (four weeks). Forty-eight (48) patients with myofascial pain were randomly assigned between actual and placebo treatments and between the energetic doses of 25 J/cm(2) and 60 J/cm(2), and were evaluated using VAS before, immediately after the final application, and 30 days after the laser treatment. Surface electromyography was performed with maximum dental clenching before and after laser therapy. The results show there were no significant statistical differences in the EMG activity between the groups before and after laser treatment. With regard to the pain at palpation, although both groups presented a significant difference in the symptoms before and after the treatment, only the active doses showed statistically significant reductions in pain level in all the regions of the palpated muscles. However, there was no significant statistical difference between groups (experimental and placebo). In conclusion, low level laser did not promote any changes in EMG activity. The treatment did, however, lessen the pain symptoms in the experimental groups.

Low Intensity Laser Therapy in Temporomandibular Disorder: a Phase II Double-Blind Study

The purpose of this study was to evaluate the analgesic effect of Low Intensity Laser Therapy (LILT) and its influence on masticatory efficiency in patients with temporomandibular dysfunction (TMD). This study was performed using a random, placebo-controlled, and double-blind research design. Fourteen patients were selected and divided into two groups (active and placebo). Infrared laser (780 nm, 70 mw, 60s, 105J/cm(2)) was applied precisely and continuously into five points of the temporomandibular joint (TMJ) area: lateral point (LP), superior point (SP), anterior point (AP), posterior point (PP), and posterior-inferior point (PIP) of the condylar position. This was performed twice per week, for a total of eight sessions, To ensure a double-blind study, two identical probes supplied by the manufacturer were used: one for the active laser and one for the inactive placebo laser. They were marked with different letters (A and B) by a clinician who did not perform the applications. A Visual Analogue Scale (VAS) and a colorimetric capsule method were employed. Data were obtained three times: before treatment (Ev1), shortly after the eighth session (Ev2), and 30 days after the first application (Ev3). Statistical tests revealed significant differences at one percent (1%) likelihood, which implies that superiority of the active group offered considerable TMJ pain improvement. Both groups presented similar masticatory behavior, and no statistical differences were found. With regard to the evaluation session, Ev2 presented the lowest symptoms and highest masticatory efficiency throughout therapy. Therefore, low intensity laser application is effective in reducing TMD symptoms, and has influence over masticatory efficiency [Ev2 (0.2423) and Ev3 (0.2043), observed in the interaction Evaluations x Probes for effective dosage].

Low-level lead exposure and children

The adverse effects of environmental lead exposure on the mental development of young children are well established. There is no safe level of blood lead below which children are not affected. Recent research expands our understanding of the impact of lead exposure continuing into later childhood, as well as its effects on children's behaviour. However, social and other environmental factors also contribute to variance in measures of developmental and behavioural outcomes. Lead is associated with only modest effects on children's development, but is a potentially modifiable risk factor. As environmental exposure to lead declines for the whole population, continued specific attention is needed for children living in industrial areas.

Long-Term Effects of Specific Stabilizing Exercises for First-Episode Low Back Pain

Study Design. A randomized clinical trial with 1-year and 3-year telephone questionnaire follow-ups. Objective. To report a specific exercise intervention’s long-term effects on recurrence rates in acute, first-episode low back pain patients. Summary of Background Data. The pain and disability associated with an initial episode of acute low back pain (LBP) is known to resolve spontaneously in the short-term in the majority of cases. However, the recurrence rate is high, and recurrent disabling episodes remain one of the most costly problems in LBP. A deficit in the multifidus muscle has been identified in acute LBP patients, and does not resolve spontaneously on resolution of painful symptoms and resumption of normal activity. Any relation between this deficit and recurrence rate was investigated in the long-term. Methods. Thirty-nine patients with acute, first-episode LBP were medically managed and randomly allocated to either a control group or specific exercise group. Medical management included advice and use of medications. Intervention consisted of exercises aimed at rehabilitating the multifidus in cocontraction with the transversus abdominis muscle. One year and three years after treatment, telephone questionnaires were conducted with patients. Results. Questionnaire results revealed that patients from the specific exercise group experienced fewer recurrences of LBP than patients from the control group. One year after treatment, specific exercise group recurrence was 30%, and control group recurrence was 84% (P , 0.001). Two to three years after treatment, specific exercise group recurrence was 35%, and control group recurrence was 75% (P , 0.01). Conclusion. Long-term results suggest that specific exercise therapy in addition to medical management and resumption of normal activity may be more effective in reducing low back pain recurrences than medical management and normal activity alone. [Key Words: multifidus, low back pain, rehabilitation]

Glycosphingolipids modulate renal phosphate transport in potassium deficiency

Background. Potassium (K) deficiency (KD) and/or hypokalemia have been associated with disturbances of phosphate metabolism The purpose of the present study was to determine the cellular mechanisms that mediate the impairment of renal proximal tubular Na/Pi cotransport in a model of K deficiency in the rat. Methods. K deficiency in the rat was achieved by feeding rats a K-deficient diet for seven days. which resulted in a marked decrease in serum and tissue K content. Results. K deficiency resulted in a marked increase in urinary Pi excretion and a decrease in the V-max of brush-border membrane (BBM) Na/Pi cotransport activity (1943 95 in control vs. 1183 +/- 99 pmol/5 sec/mg BBM protein in K deficiency. P < 0.02). Surprisingly. the decrease in Na/Pi cotransport activity was associated with increases in the abundance of type I (NaPi-1). and type II (NaPi-2) and type III (Glvr-1) Na/Pi protein. The decrease in Na/Pi transport was associated with significant alterations in BBM lipid composition, including increases in sphingomyelin. glucosylceramide. and ganglioside GM, content and a decrease in BBM lipid fluidity. Inhibition of glucosylceramide synthesis resulted in increases in BBM Na/Pi cotransport activity in control and K-deficient rats. The resultant Na/Pi cotransport activity in K-deficit nt rats was the same as in control rats (1148 +/- 52 in control + PDMP vs. 11.52 +/- 61 pmol/5 sec/mg BBM protein in K deficiency + PDMP). These changes in transport activity occurred independent of further changes in BBM NaPi-2 protein or renal cortical NaPi-2 mRNA abundance. Conclusion. K deficiency in the rat causes inhibition of renal Na/Pi cotransport activity by post-translational mechanisms that are mediated in part through alterations in glucosylceramide content and membrane lipid dynamics.

Properties and function of KCNQ1 K+ channels isolated from the rectal gland of Squalus acanthias

KCNQ1 (K(V)LQT1) K+ channels play an important role during electrolyte secretion in airways and colon. KCNQ1 was cloned recently from NaCl-secreting shark rectal glands. Here we study. the properties and regulation of the cloned sK(V)LQT1 expressed in Xenopus oocytes and Chinese hamster ovary (CHO) cells and compare the results with those obtained from in vitro perfused rectal gland tubules (RGT). The expression of sKCNQ1 induced voltage-dependent, delayed activated K+ currents, which were augmented by an increase in intracellular cAMP and Ca2+. The chromanol derivatives 293B and 526B potently inhibited sKCNQ1 expressed in oocytes and CHO cells, but had little effect on RGT electrolyte transport. Short-circuit currents in RGT were activated by alkalinization and were decreased by acidification. In CHO cells an alkaline pH activated and an acidic pH inhibited 293B-sensitive KCNQ1 currents. Noise analysis of the cell-attached basolateral membrane of RGT indicated the presence of low-conductance (

NMR structure and backbone dynamics of a concatemer of epidermal growth factor homology modules of the human low-density lipoprotein receptor

The ligand-binding region of the low-density lipoprotein (LDL) receptor is formed by seven N-terminal, imperfect, cysteine-rich (LB) modules. This segment is followed by an epidermal growth factor precursor homology domain with two N-terminal, tandem, EGF-like modules that are thought to participate in LDL binding and recycling of the endocytosed receptor to the cell surface. EGF-A and the concatemer, EGF-AB, of these modules were expressed in Escherichia coli. Correct protein folding of EGF-A and the concatemer EGF-AB was achieved in the presence or absence of calcium ions, in contrast to the LB modules, which require them for correct folding. Homonuclear and heteronuclear H-1-N-15 NMR spectroscopy at 17.6 T was used to determine the three-dimensional structure of the concatemer. Both modules are formed by two pairs of short, anti-parallel beta -strands. In the concatemer, these modules have a fixed relative orientation, stabilized by calcium ion-binding and hydrophobic interactions at the interface. N-15 longitudinal and transverse relaxation rates, and {H-1}-N-15 heteronuclear NOEs were used to derive a model-free description of the backbone dynamics of the molecule. The concatemer appears relatively rigid, particularly near the calcium ion-binding site at the module interface, with an average generalized order parameter of 0.85 +/- 0.11. Some mutations causing familial hypercholesterolemia may now be rationalized. Mutations of D41, D43 and E44 in the EGF-B calcium ion-binding region may affect the stability of the linker and thus the orientation of the tandem modules. The diminutive core also provides little structural stabilization, necessitating the presence of disulfide bonds. The structure and dynamics of EGF-AB contrast with the N-terminal LB modules, which require calcium ions both for folding to form the correct disulfide connectivities and for maintenance of the folded structure, and are connected by highly mobile linking peptides. (C) 2001 Academic Press.

Thermal characterization of copolymers obtained by radiation grafting of styrene onto poly(tetrafluoroethyleneperfluoropropylvinylether) substrates: thermal decomposition, melting behavior and low-temperature transitions

Differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA) have been used to study the thermal decomposition, the melting behavior and low-temperature transitions of copolymers obtained by radiation-induced grafting of styrene onto poly (tetrafluoroethylene- perfluoropropylvinylether) (PFA) substrates. PFA with different contents of perfluoropropylvinylether (PPVE) as a comonomer have been investigated. A two step degradation pattern was observed from TGA thermograms of all the grafted copolymers, which was attributed to degradation of PSTY followed by the degradation of the PFA backbone at higher temperature. One broad melting peak can be identified for all copolymers, which has two components in the samples with higher PPVE content. The melting peak, crystal-crystal transition and the degree of crystallinity of the grafted copolymers increases with radiation grafting up to 50 kGy, followed by a decrease at higher doses. No such decrease was observed in the ungrafted PFA samples after irradiation. This indicated that the changes in the heats of transitions and crystallinity at low doses are due to the radiation effects on the microstructure of PFA (chain scission), whereas at higher doses the grafted PSTY is the driving force behind these changes. (C) 2001 Elsevier Science Ltd. All rights reserved.