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PubMed1985

Studies of Root Function in Zea mays: IV. Effects of Applied Pressure on the Hydraulic Conductivity and Volume Flow through the Excised Root.

The volume flux, J(v), and the osmotic driving force, sigma big up tri, openpi, across excised root systems of Zea mays were measued as a function of big up tri, openP, the hydrostatic pressure difference applied across the root, using the pressure jump method previously described (Miller DM 1980 Can J Bot 58: 351-360). J(v) varied from 5.3% to 142% of its value in intact transpiring plants as a result of the application of pressure differences from -2.4 to 2.4 bar. The calculated hydraulic conductivity was 5.9 x 10(-4) cubic centimeters per second per bar per gram root and was independent of pressure. A model of root function similar to those appearing in the literature failed to provide quantitative accord with the data. A proposed model, which includes the effect of volume flux on the distribution of solutes in the symplasm, predicts accurately J(v) big up tri, openpi, and the xylem solute concentration as a function of big up tri, openP.

Journal Article↗
PubMed2001

NEXAFS study of 1-butanethiol adsorbed on Cu(111) and square root of 7 x square root of 7 R19.1 degrees S/Cu(111).

The adsorption of 1-butanethiol on Cu(111) and square root of 7 x square root of 7 R19.1 degrees S/Cu(111) surfaces has been studied by S K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy and thermal desorption spectroscopy. Upon adsorption on clean Cu(111) surface at room temperature, butanethiolate as well as atomic sulfur is formed. For the butanethiolate, the S-C bond is found predominately perpendicular to the surface as revealed by polarization analysis. In contrast, on square root of 7 x square root of 7 R19.1 degrees S/Cu(111) surface, the S-H and S-C bonds of the butanethiol stay intact, resulting in a weakly chemisorbed butanethiol.

Adsorption↗
PubMed2000

[The expression of trkC in spared dorsal root ganglion following unilateral dorsal root rhizotomy].

This study sought to explore the expression of trkC in spared dorsal root ganglion(DRG) following unilateral dorsal root rhizotomy. 15 cats were divided into three groups: the intact group, the 3-day and 10-day groups after operation (unilaterral L1-L5 DRG and L7-S2 DRG were sectioned, but L6 DRG was spared). The animals were sacrificed on the 3rd day and 10th day after operation, respectively. The L6 DRG from the three groups were taken and cut into frozen sections (20 microns). The sections were stained using specific antiserum for trkC by the immunohistochemical ABC method. The numbers of large sized neurons (> 57 microns) and small sized neurons (< 42 microns) for trkC-IR were counted respectively. The results showed that the number of positive large sized neurons for trkC of the 10-day group after operation decreased significantly than that of the intact group and the 3-day group after operation, while the number of positive small sized neurons for trkC of the 10-day group increased apparently than that of the intact group and the 3-day group after operation (P < 0.05). This experiment demonstrated that unilateral partial dorsal root rhizotomy could change the expression of trkC might in large neurons and small sized neurons, and the results suggested that trkC might involve in the spinal cord plasticity following partial dorsal root rhizotomy.

Animals↗
PubMed2005

[Expression of CNTF and PDGF in spared dorsal root ganglion after partial dorsal root rhizotomy].

OBJECTIVE: To investigate the expression of ciliary neurotrophic factor (CNTF) and platelet derived growth factor (PDGF) in spared dorsal root ganglion (DRG) after partial dorsal root rhizotomy. METHODS: Twenty adult cats were divided into four groups. Five cats were kept intact in the control group. Fifteen cats were subjected to bilateral root rhizotomy, and on the 3rd day, 7th day and 14th day after operation, they were sacrificed as subjects in the three experiment groups respectively (n=5 per group) and their DRGs (L6) were taken. Immunochemical ABC method was used to detect the distribution of CNTF and PDGF-immunoreactivity neurons in those DRGs. The quantitative analysis was conducted to get the numbers of CNTF, PDGF-positive total, large, and medium-small sized neurons in each group. RESULTS: CNTF, PDGF-immunoreactants were distributed in large and medium-small sized neurons. The numbers of total and medium-small sized CNTF positive neurons were noted to be decreased on the 3rd day after operation (P<0.05), and no difference 7th and 14th days was seen when compared with control (P>0.05), but the large positive neurons showed no difference. The total and medium-small sized PDGF positive neurons were found decreased apparently on the 3rd day and 7th day, but there was no difference on the 14th day as compared with normal level. Large positive neurons displayed no change at every time. CONCLUSION: Partial dorsal root rhizotomy exerts different influence on the expression of CNTF and PDGF for different neurons in spared DRG.

Animals↗
PubMed1991

N-Acetylglutamic acid: an extracellular nod signal of Rhizobium trifolii ANU843 that induces root hair branching and nodule-like primordia in white clover roots.

An extracellular metabolite purified from Rhizobium trifolii ANU843 was established as N-acetylglutamic acid (GluNAc) by 1H NMR and Fourier transform IR spectroscopy, gas chromatography/mass spectrometry of its methylated product, and organic synthesis. TLC analyses indicated that extracellular accumulation of GluNAc by R. trifolii ANU843 grown in defined BIII culture medium was dependent on induction of its bacterial nodulation (nod) genes and the positive regulatory gene nodD on its symbiotic plasmid. 1H NMR analyses showed less GluNAc in fractionated culture supernatants of nodL and nodM mutant derivatives of R. trifolii ANU843. GluNAc induced three morphological responses on axenic roots of white clover seedlings: (i) root hair branching; (ii) tip swelling followed by resumed elongation of root hairs; and (iii) a slight increase in foci of cortical cell divisions, which developed into nodule-like primordia. These biological activities of extracellular GluNAc from R. trifolii ANU843 were confirmed with authentic standards of GluNAc. These results indicate that extracellular accumulation of N-acetylglutamic acid is linked to flavone-dependent metabolism involving nodD, nodL, and nodM in R. trifolii ANU843. This constitutes the first report on the structure of a nod-dependent extracellular signal from R. trifolii that can affect root hair and nodule development in white clover and whose biological activity on this host has been confirmed with authentic standards.

Flavonoids↗
PubMed1995

A histocytological study of the rat hair follicle--an appraisal of a monocellular layer ("middle root sheath") between inner and outer root sheaths.

Hair follicles of male Wistar rats in the anagen stage were examined by light and electron microscopy. A distinct monocellular layer was identified between the Henle's layer and the outer root sheath (ORS). In the lower part of the ORS, this cell layer is more closely bound to the inner root sheath (IRS) than to the ORS, while in the upper half the situation is reversed. Electron density and staining property of this layer are gradually changed according to regions of the hair follicle which may indicate the metabolic conditions of the organism. The origin of this layer can be traced back to the germinal matrix directly facing the neck of the hair papilla. Findings are also reported about the gaps formed between the cells of Henle's layer after keratinization and about the contact formed between the cells of Huxley's layer and the cells of this monocellular layer through these gaps. Our observation reported in this study strongly suggests that this layer belongs neither to the IRS nor to the ORS, but that it represents an independent layer of cells. Therefore we propose to name this layer the "middle root sheath." This middle root sheath may serve the following three functions: 1) alleviation of intrinsic friction generated by colliding cell dynamics between the IRS and the ORS, 2) deterrence of keratinization of the ORS after exfoliation of the IRS and 3) secretion and excretion of metabolites.

Animals↗
PubMed1980

The effect of root resection on the sealing property of root canal obturations.

Root canal systems of extracted anterior teeth were obturated with sealer and either multiple gutta-percha cones or single silver cones. The effect of root resection on the sealing property of these obturating materials was evaluated by autoradiographic methods. Results indicate that root resection with a rotary instrument in a high-speed handpiece does not adversely affect the sealing property of well-condensed gutta-percha-sealer obturations.

Apicoectomy↗
PubMed2005

Physical properties of root cementum: Part 5. Volumetric analysis of root resorption craters after application of light and heavy orthodontic forces.

BACKGROUND: In previous studies on root resorption, resorption was quantified by making histologic cuts or by surface area measurements of resorption craters. The aims of this study were to evaluate the effects of orthodontic force magnitude on root resorption craters with volumetric measurements and also to identify the sites that might be predisposed to resorption. METHODS: After an experimental time of 28 days, 36 human premolars previously divided into light-force (25 g) and heavy-force (225 g) groups were extracted and prepared for scanning electron microscope imaging. Pairs of stereo images were taken, and 3-dimensional quantitative volumetric analysis was performed with commercial software. RESULTS AND CONCLUSIONS: The mean volume of the resorption crater in the light-force group was 3.49-fold greater than in the control group; the mean volume of the resorption crater in the heavy-force group was 11.59-fold greater than in the control group ( P < .001). The heavy-force group had 3.31-fold greater total resorption volume than the light-force group ( P < .001). Buccal cervical and lingual apical regions had significantly more resorption craters than the other regions ( P < .001). There was more resorption by volume in the heavy-force group compared with the light-force group and controls. Although more resorption was recorded in the light-force group, the difference in the amount of resorption between the light-force and control groups was not statistically significant. There was significantly more resorption on the buccal cervical and lingual apical regions of the root surfaces than on the other regions, suggesting that high-pressure zones might be more susceptible to resorption after 28 days of force application.

Adolescent↗
PubMed2005

A comparative prospective randomized clinical study of MTA and IRM as root-end filling materials in single-rooted teeth in endodontic surgery.

OBJECTIVE: Randomized clinical prospective study to evaluate the application of MTA and IRM as retrograde sealers in surgical endodontics. STUDY DESIGN: One hundred single-rooted teeth were surgically treated. After randomization, MTA or IRM was used as a retrosealer. Radiographs were taken 1 week, 3 months, and 1 year postoperatively. Assessment was performed by 2 independent assessors 1 year after surgery. Both treatment groups were homogeneous in their composition, and clinical features and radiographic findings were classified according to Rud's classification. RESULTS: Complete healing was observed in 64% of the MTA-treated teeth vs 50% of the IRM-treated teeth. Incomplete healing was seen in 28% (MTA) vs 36% (IRM), and unsatisfactory in 6% (MTA) vs 14% (IRM). Only 1 failure was seen (MTA). No statistically significant differences were found between the 2 retrofilling materials. CONCLUSION: As root-end filling materials in this clinical prospective randomized design on single rooted teeth, MTA and IRM had the same clinical effectiveness.

Adolescent↗
PubMed1996

Healing of the root surface-associated periodontium: an immunohistochemical study of orthodontic root resorption in man.

The purpose of the present investigation was to study resorption and regeneration of periodontal tissues incident to orthodontic tooth movement, in particular cells resorbing the root surface and the subsequent regeneration of the periodontal epithelial network and forming reparative cementum. The study was carried out using a select number of immunohistochemical markers on extracted human teeth which had been treated orthodontically. The most striking finding in the resorbing areas was the presence of what appeared to be two populations of KP 1+ mononuclear cells located at a distance of 50-100 microns from the root surface and multinucleated cells in resorption lacunae in close contact with the root surface. KP 1+ has previously not been reported for odontoclasts. The mononuclear KP 1+ cells in the periodontal ligament may represent either precursors to odontoclasts or phagocytic scavenger cells of the macrophage lineage. The subsequent healing of the resorption lacunae was characterized by re-establishment of nervous, vascular and epithelial tissues as evidenced by S-100+ filamentous delicate structures, factor VIII+ vessels and cytokeratin+ clusters of cells, respectively. However, cytokeratin+ single cells in close contact with the unresorbed cementum did not re-appear within the healing period. Although the present results are not quantitative in nature, cementoblasts located in the vicinity of resorption lacunae, especially healing ones, appeared to show an up-regulation of epidermal growth factor (EGF) receptors. It may be suggested the intense positive staining for EGF receptors may be an expression of an auto- or paracrine stimulatory pathway increasing the rate of reparative cementum formation.

Adolescent↗
PubMed1996

Root caries and root defects in urban and rural adults: the Florida Dental Care Study.

As part of the Florida Dental Care Study--a longitudinal study of risk factors for changes in dental health--the authors examined and interviewed 873 adults aged 45 years and older. During the examination, clinicians noted the number of teeth present and the participant's dental condition, including presence of root caries and fillings or noncarious defects on the roots. The interview was conducted to collect demographic and other information such as the adults' perceptions about dental care and their perceptions about their own dental health. The authors found that men, African-Americans, adults living in rural areas and those living in poverty were significantly more likely to have root caries than other participants. The data reported in this article will serve as baseline information for subsequent research.

Aged↗
PubMed2006

Root canal therapy of a maxillary first molar with five root canals: case report.

This paper reports the case of a maxillary left first molar that presented three root canals in the mesiobuccal root. Root canal therapy and case management are described. Features like wide crown access, adequate illumination and use of exploring files where important for successful completion of the endodontic treatment.

Adolescent↗
PubMed1976

[Results and consequences of clinical-radiological follow-up studies of root canal treated teeth. 2. Dependence of the results on age, degree of root canal obturation and devitalizing drugs. Conclusions for the dental practice].

The authors report of the follow-up examination of root-canal treatments performed at the Policlinic of Conservative Stomatology of the Karl Marx University of Leipzig in 1967, in which 499 teeth were assessed using severe criteria. The results obtained from the various diagnostic groups depended on the age and the degree of root-filling. Of the root-canal treatment techniques employed, devitalization by means of arsenic showed the highest failure rate. Conclusions relevant to stomatological practice are drawn from the results presented in the two parts of this study.

Age Factors↗
PubMed1996

[In vitro comparative study of instruments for root canal preparation. IV. Correlations between the original shape of the root canal and the asymmetry resulting from the preparation].

Certain asymmetry of root canal preparation can be observed in the straight root canal group, as well. The modification of original root canal shape in this group usually is not substantial. Using hand instruments for shaping curved canals special tecniques are required to minimize the asymmetry. Though tendencies of different shaping characteristics can be observed on the mesiodistal and oro-vestibular views there are no statistically significant differences between the asymmetries measured on the oro-vestibular and mesio-distal views. The three dimensional form of canals usually exclude the possibility of forming the same asymmetry on both projections, but the difference between the two views is not striking, therefore the conventional clinical radiographs usually do not give complete information about the asymmetry of preparation.

Dental Instruments↗
PubMed1999

Chemicals from roots, hairy roots, and their application.

Plants produce thousands of different compounds through the secondary metabolism pathways. Since many of these products are obtained by direct extraction from plants that are cultivated in the field or some times even collected in their original habitat several factors can alter their yield. The use of plant cell cultures has overcome several inconveniences for the production of secondary metabolites. Organized cultures, and especially root cultures, can make a significant contribution to our understanding of secondary metabolism. Furthermore, a new alternative has arisen: transformed root cultures. Until now, hairy roots have been obtained from more than 100 different species. The products that they are able to produce range from alkaloids to aromatic compounds and dyes. These kinds of cultures have turned out to be an invaluable tool to study the biochemistry and the gene expression of the metabolic pathways in order to elucidate the intermediaries and enzymes involved in the biosynthesis of secondary metabolites.

Animals↗
PubMed1996

Isolation of a root-specific cDNA encoding a ns-LTP-like protein from the roots of bean (Phaseolus vulgaris L.) seedlings.

A root-specific cDNA clone, PVR3, was isolated from a bean (Phaseolus vulgaris L.) root cDNA library by a differential screening procedure. The nucleotide sequence of PVR3 contains an open reading frame coding for an 11.14 kDa polypeptide of 102 amino acid residues; the first 25 amino acids correspond to the sequence characteristic of a signal peptide. Comparison of the deduced PVR3 polypeptide sequence with the polypeptide sequences of previously cloned genes indicates that PVR3 may encode a ns-LTP-like protein. Molecular modelling of the PVR3 protein predicts that it has a three-dimensional structure that is similar to the three-dimensional model determined from the maize ns-LTP. The PVR3 mRNA accumulated mainly in the roots of young seedlings. It can be detected at low levels in flowers, but it is not detected in other organs. Genomic Southern blot analysis indicates that the genomic DNA corresponding to PVR3 cDNA is encoded by a single gene or small gene family in the bean genome.

Amino Acid Sequence↗
PubMed1986

Frequency of accumulation of filaments in adaxonal cytoplasm of Schwann cells of myelinated fibers of rat spinal roots. Comparison between ventral and dorsal roots and between growing and mature rats.

The frequency of accumulation of 6-nm filaments in the adaxonal cytoplasm of Schwann cells in the 6th lumbar dorsal and ventral roots was evaluated in 4-, 8-, 26- and 45-week-old Sprague-Dawley rats. The frequency was higher in 4- and 8-week-old (growing) rats than in 26- and 45-week-old (mature) rats, and also higher in ventral than in dorsal roots in 4-, 8- and 26-week old rats. There were no clusters on certain groups of myelinated fibers according to the size of transverse axonal area, in both the ventral and dorsal roots. Therefore, this accumulation may reflect certain functions of the adaxonal cytoplasm of Schwann cell during natural growth and maturation of the axon and myelin sheath.

Aging↗
PubMed1991

The role of the prosthodontist in restoring root-resected molars: a study of 70 molar root resections.

Root resection is a complex, multidiscipline technique to eliminate molar furcation invasions. In the short term of 3 or 4 years it has been highly successful, but after 10 years approximately one third fail. A substantial number of failures were attributed to recurrent periodontal disease. This study examined 70 root resected molars in 62 patients for the quality of the resections. Twenty-one (30%) of the resections were considered faulty when subgingival, residual roots, furcal lips, and/or ledges were present. Failures were more frequent in maxillary molars (33.3%) than mandibular molars (22.7%). Clinically hidden roots/lips and ledges in mandibular molars were readily observed in radiographs, but were seen radiographically only 37.5% of the time in maxillary molars. Since subgingival defects are believed to encourage future periodontal disease, it is important that the dentist detect these structures and correct them before proceeding with the permanent restoration.

Adult↗