A comparison of the effectiveness of chloroform and eucalyptus oil in dissolving root canal sealers.

Objective: The solubility of 8 different root canal sealers in chloroform and in eucalyptus oil was compared.

Study Design: For standardized samples (n=12), ring molds were filled with mixed sealers based on epoxy resin, silicone, calcium hydroxide, zinc oxide-eugenol, glass ionomer, and polyketone. These samples were immersed in chloroform or eucalyptus oil for 30 seconds, 1 minute, 2 minutes, 5 minutes, 10 minutes, and 20 minutes.

A college nutrition science course as an intervention to prevent weight gain in female college freshmen.

The objective of this study was to test the hypothesis that a nutrition course that stresses fundamental principles of human physiology, energy metabolism, and genetics helps prevent weight gain during the first 16 months of college life. A randomized control trial was conducted from January 1997 to May 1998 using volunteers. Forty female college freshmen participated in the intervention (college course, n = 21) and control (no course, n = 19) groups.

Roentgenographic investigation of frequency and degree of canal curvatures in human permanent teeth.

Canal curvatures of 700 permanent human teeth were determined by measuring the angle and the radius of the curvatures and the length of the curved part of the canal. For each type of tooth (except third molars) 50 were selected at random and were investigated. Size 08 silver points were inserted into the canals, and the teeth were radiographed from a facial and proximal view by using a standardized technique.

Inactivation of the phloem-specific Dof zinc finger gene DAG1 affects response to light and integrity of the testa of Arabidopsis seeds.

We show here that seeds from the knockout mutant of the Arabidopsis DAG1 gene encoding a Dof zinc finger transcription factor have an altered response to red and far-red light. Mutant dag1 seeds are induced to germinate by much lower red light fluence rates, and germination reaches more quickly a point where it is independent of phytochrome signaling. Moreover, although microscopic analysis reveals no obvious structural alterations in the seed coat (testa) of dag1 seeds, staining assays with different dyes point to an abnormal fragility of the testa.

Phytochrome E controls light-induced germination of Arabidopsis.

Germination of Arabidopsis seeds is light dependent and under phytochrome control. Previously, phytochromes A and B and at least one additional, unspecified phytochrome were shown to be involved in this process. Here, we used a set of photoreceptor mutants to test whether phytochrome D and/or phytochrome E can control germination of Arabidopsis.

Antimicrobial efficacy of chloroxylenol and chlorhexidine in the treatment of infected root canals.

Purpose: To investigate the antimicrobial efficacy of a chlorhexidine gluconate (2.0%) and of an ethanolic chloroxylenol solution (10%) as a temporary root canal dressing against selected test microorganisms (Staphylococcus aureus, Streptococcus faecium, Escherichia coli, Candida albicans).

Materials And Methods: Extracted single-rooted human teeth were instrumented up to size 40.

Interaction of the response regulator ARR4 with phytochrome B in modulating red light signaling.

The Arabidopsis thaliana response regulator 4, expressed in response to phytochrome B action, specifically interacts with the extreme amino-terminus of the photoreceptor. The response regulator 4 stabilizes the active Pfr form of phytochrome B in yeast and in planta, thus elevates the level of the active photoreceptor in vivo. Accordingly, transgenic Arabidopsis plants overexpressing the response regulator 4 display hypersensitivity to red light but not to light of other wavelengths.

Isolation and characterization of four novel parsley proteins that interact with the transcriptional regulators CPRF1 and CPRF2.

The common plant regulatory factors (CPRFs) from parsley are transcription factors with a basic-leucine-zipper motif that bind to cis-regulatory elements frequently found in promoters of light-regulated genes. Proposed to function in concert with members of other transcription factor families, CPRFs regulate the transcriptional activity of many target genes. Here, we report that, in contrast to CPRF2, which operates as a transcriptional activator, CPRF1 functions as repressor in vivo.

Shaping ability of Hero 642 rotary nickel-titanium instruments and stainless steel hand K-Flexofiles in simulated curved root canals.

Objective: The purpose of this study was to compare the shaping ability of Hero 642 rotary nickel-titanium instruments with that of stainless steel hand K-Flexofiles.

Study Design: Simulated 28 degrees and 35 degrees curved canals were prepared with Hero 642 instruments by using a crown-down preparation and with K-Flexofiles by using a reaming working motion (n = 24 canals in each case). All canals were sequentially prepared up to size 35.

Smoking policies in manufacturing and assembly workplaces, Wisconsin, 1999.

Although Wisconsin's clean indoor air law prohibits or restricts smoking in certain areas, it specifically exempts manufacturing and assembly workplaces from its provisions. We conducted a mail survey of 1500 randomly selected employers to determine the nature and extent of smoking policies in Wisconsin's blue-collar workforce. Of the 1042 (70%) respondents, 49% prohibit all smoking; 26% allow smoking only in designated areas; 18% allow smoking in all areas except designated non-smoking areas; and 7% allow smoking anywhere.

Relationship between design features of endodontic instruments and their properties. Part 3. Resistance to bending and fracture.

Stainless-steel prototypes characterized by five different cross-sectional shapes (square, triangular, rhomboidal, "S"-shaped, and the cross-sectional design of H-type files) and three different number of flutes (16, 24, and 32) were used for investigation of the relationship between design features and the resistance to bending and fracture of root canal instruments. Both resistance to bending (bending moment) and resistance to fracture (angular deflection and torque) were determined in accordance to ISO 3630-1. Numbers 15, 25, and 35 prototypes were tested with a sample size of 10 instruments each.

pH changes in root dentin after root canal dressing with gutta-percha points containing calcium hydroxide.

Alkalinizing action on root dentin was investigated by treating the enlarged root canals of a total of 120 extracted teeth for 24 h, 3 days, or 7 days with either gutta-percha points (size 40) containing calcium hydroxide or an equivalent quantity of aqueous calcium hydroxide suspension. After splitting the teeth longitudinally the pH of the dentin was determined using a pH microelectrode in small cavities at each of four set measuring points. The gutta-percha points were unable to alkalinize the root dentin over a period of 7 days.

A comparative scanning electron microscopic investigation of the efficacy of manual and automated instrumentation of root canals.

The cleaning effectiveness of automated and manual root canal instrumentation was investigated with the aid of a scanning electron microscope. Hand instrumentation was performed with K-Flexofiles used in a reaming working motion and according to the step-back technique and with Hedstrom files used in a filing motion. Automated preparation was performed with the KaVo-Endo Flash device featuring torque-limited rotation using K-Flexofiles, as well as with the mechanical ProFile system using rotary nickel-titanium instruments.

Recombinant phytochrome A in yeast differs by its spectroscopic and photochemical properties from the major phyA' and is close to the minor phyA": evidence for posttranslational modification of the pigment in plants.

Previously, two pools of phytochrome A (phyA' and phyA") have been detected by in situ low-temperature fluorescence spectroscopy and photochemistry; it was suggested that they might differ in the nature of their posttranslational modification. In order to verify this possibility Arabidopsis and rice (Oryza) phyA were expressed in yeast and the pigments were assembled in vivo with phycocyanobilin (PCB) and phytochromobilin (P phi B). The resulting recombinant phytochromes in the red-light-absorbing form (Pr) were characterized in the yeast cell by (1) the fluorescence emission spectra; (2) the temperature dependence of Pr fluorescence intensity and activation energy of fluorescence decay; and (3) the extent of photoconversion of Pr into photoproduct lumi-R (gamma 1) or far-red-light absorbing form (Pfr) (gamma 2).

The response regulator ARR2: a pollen-specific transcription factor involved in the expression of nuclear genes for components of mitochondrial complex I in Arabidopsis.

Two-component signal systems regulate a variety of cellular activities. They involve at least two common signalling molecules: a signal-sensing kinase and a response regulator that mediates the output response. Multistep systems also require proteins containing phosphotransfer domains.

EID1, an F-box protein involved in phytochrome A-specific light signaling.

To perceive red and far-red light, plants have evolved specific photoreceptors called phytochromes. Even though the spectral properties of all phytochromes are very similar, they show a distinct mode of action. Here we describe EID1, a negatively acting component of the signaling cascade that shifts the responsiveness of the phytochrome A (phyA) signaling system associated with hypocotyl elongation from red to far-red wavelengths.

Event-by-event fluctuations of the Kaon-to-Pion ratio in central Pb+Pb collisions at 158 GeV per nucleon.

We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition.

Effect of transcutaneous electrical nerve stimulation on pain perception threshold of human teeth: a double-blind, placebo-controlled study.

In this double-blind, placebo-controlled study, we studied the effect of three different transcutaneous electrical nerve stimulation (TENS) devices with extra- and intraoral electrodes on the pain perception thresholds of 234 unrestored, caries-free human teeth of 66 healthy individuals subjected to stimulation with an electric pulp tester. A placebo control collective of 64 healthy subjects received no electrical stimulation, since an inactive TENS device was used. In all tooth types tested (maxillary and mandibular incisors and premolars), the use of the active TENS devices resulted in an increase of 16.

Malformations in maxillary incisors: case report of radicular palatal groove.

This report describes malformations of anterior teeth and a case of a palatal radicular groove in an upper lateral incisor with periodontal complications. The patient was first diagnosed with an endodontic problem. Endodontic treatment alone failed to resolve the pain.

Intracellular trafficking of photoreceptors during light-induced signal transduction in plants.

Plants monitor changes in the ambient light environment by highly specialised photoreceptors, which include the red/far-red photoreversible phytochromes, the blue-light-absorbing cryptochromes and phototropin and the so-far-unidentified UVB photoreceptor(s). Light easily penetrates plant organs/tissues and reaches even the subcellular compartments of various cell types. Therefore, it is not surprising that the determination of the intracellular localisation of photoreceptors has been, for many years, a major, and often controversial, subject of plant photobiology and cell biology research.

Negative interference of endogenous phytochrome B with phytochrome A function in Arabidopsis.

To study negative interactions between phytochromes, phytochrome B (phyB) overexpressor lines, the mutants phyA-201, phyB-4, phyB-5, phyD-1, phyA-201 phyB-5, phyA-201 phyD-1, and phyB-5 phyD-1 of Arabidopsis were used. Endogenous phyB, but not phytochrome D (phyD), partly suppressed phytochrome A (phyA)-dependent inhibition of hypocotyl elongation in far-red light (FR). Dichromatic irradiation demonstrated that the negative effect of phyB was largely independent of the photoequilibrium, i.

Nucleo-cytoplasmic partitioning of the plant photoreceptors phytochromes.

Phytochromes in harmony with blue light photoreceptors play a major role in controlling plant growth and development from germination to seed maturation. Light absorption by phytochromes triggers a signaling cascade, phototransduction, which culminates in regulated gene expression. A major regulatory step at the cellular level, which affects specificities of light-induced physiological responses, seems to be the light-quality and light-quantity dependent nuclear import of the phytochromes themselves.

Both subunits of the dimeric plant photoreceptor phytochrome require chromophore for stability of the far-red light-absorbing form.

The dimeric plant photoreceptor phytochrome is converted from its inactive red light-absorbing form (Pr) into the active far-red light-absorbing form (Pfr) upon light absorption. Dynamics of Pfr generation and of thermal Pfr-to-Pr conversion are of fundamental importance for inducing adequate responses to light signals. Here, we analyzed the role of subunit interactions on spectroscopic properties of dimeric phytochrome A.

The DNA binding properties of the parsley bZIP transcription factor CPRF4a are regulated by light.

The common plant regulatory factors (CPRFs) from parsley are transcription factors with a basic leucine zipper motif that bind to cis-regulatory elements frequently found in promoters of light-regulated genes. Recent studies have revealed that certain CPRF proteins are regulated in response to light by changes in their expression level and in their intracellular localization. Here, we describe an additional mechanism contributing to the light-dependent regulation of CPRF proteins.

Control of nuclear import and phytochromes.

The past year has brought significant changes in our understanding of the molecular mechanism of photoreceptor-regulated gene expression in higher plants. The light-quantity- and light-quality-dependent nuclear import of phytochromes, followed by the conformation-dependent direct interaction of these phytochromes with transcription factors, seems to play a major role in light-modulated plant growth and development.