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At least 199 records · Page 11Linked to original sources
PubMed2000

Hypoglycaemic neuropathy in diabetic BB/Wor rats treated with insulin implants affects ventral root axons but not dorsal root axons.

It is believed that hyperglycaemia underlies diabetic neuropathy. However, low blood glucose values may also cause pathological changes in peripheral nerves and in neuronal perikarya. This study examined spinal roots, dorsal root ganglia and the ventral horn at the segmental level L5 in long-term insulin-treated eu-/hypoglycaemic diabetic rats with an obvious plantar nerve pathology. The purpose was to determine whether hypoglycaemic neuropathy affects sensory and/or motor neurons at root and/or perikaryal levels. Electron microscopic examination of dorsal roots from eu-/hypoglycaemic rats showed a normal qualitative morphology and normal numbers of unmyelinated and myelinated axons. In ventral roots the picture varied. Whereas two rats exhibited an essentially normal morphology, three rats presented moderate or marked signs of pathology such as clusters of small and medium-sized myelinated axons, medium-sized myelinated axons with abnormally thin sheaths, large unmyelinated axons and signs of past or ongoing axonal degeneration. Light microscopic examination of the L5 dorsal root ganglion and ventral horn showed a qualitatively normal picture in eu-/hypoglycaemic rats and the mean number of large ventral horn neurons per section was normal. These results suggest that the type of eu-/hypoglycaemia examined here affects ventral root axons but not dorsal root axons, that the degree of ventral root pathology is variable and that sensory and motor neuron perikarya do not appear to be affected.

Animals↗
PubMed2000

Abscisic acid and hydraulic conductivity of maize roots: a study using cell- and root-pressure probes.

Using root- and cell-pressure probes, the effects of the stress hormone abscisic acid (ABA) on the water-transport properties of maize roots (Zea mays L.) were examined in order to work out dose and time responses for root hydraulic conductivity. Abscisic acid applied at concentrations of 100-1,000 nM increased the hydraulic conductivity of excised maize roots both at the organ (root Lp(r): factor of 3 4) and the root cell level (cell Lp: factor of 7-27). Effects on the root cortical cells were more pronounced than at the organ level. From the results it was concluded that ABA acts at the plasmalemma, presumably by an interaction with water channels. Abscisic acid therefore facilitated the cell-to-cell component of transport of water across the root cylinder. Effects on cell Lp were transient and highly specific for the undissociated (+)-cis-trans-ABA. The stress hormone ABA facilitates water uptake into roots as soils start drying, especially under non-transpiring conditions, when the apoplastic path of water transport is largely excluded.

Abscisic Acid↗
PubMed1987

The population of the dorsal root ganglion cells which have central processes in ventral root and their immunoreactivity.

Axonal transport of fluorescent dyes applied to the cut distal ends of rat L4 dorsal and ventral spinal roots was studied in order to characterize the population of dorsal root ganglion (DRG) neurons emitting axons entering the ventral root. Ca. 9% of DRG neurons, principally of small or medium size, can be labeled from the ventral root, and 55% of these display immunoreactivity for the most ubiquitous DRG neuropeptide, calcitonin gene-related peptide (CGRP). Attempts to simultaneously label cut dorsal and ventral roots revealed that double labeling was exceedingly rare and that dorsal root labeling was markedly reduced. The results are consistent with previous reports of small DRG cells emitting axons which loop into the ventral root before entering the spinal cord via the dorsal root. The few cells labeled simultaneously from cut dorsal and ventral roots indicate that axonal bifurcation distal to the DRG is very rare.

Afferent Pathways↗
PubMed2006

Physical properties of root cementum: part 8. Volumetric analysis of root resorption craters after application of controlled intrusive light and heavy orthodontic forces: a microcomputed tomography scan study.

INTRODUCTION: Intrusion is a critical type of orthodontic tooth movement in relation to external root resorption. Our aims in this prospective randomized clinical trial were to quantify, 3 dimensionally, the amount of root resorption when controlled light and heavy intrusive forces were applied to human premolars and to establish the sites where root resorption is more prevalent. METHODS: Fifty-four maxillary first premolars, orthodontically indicated for extraction from 27 patients (left and right maxillary first premolars from each), were intruded for 28 days with buccal and palatal beta-titanium-molybdenum alloy 0.017 x 0.025-in cantilever springs. The patients were randomly divided into 3 groups, and various levels of force were used: group 1, heavy force (225 g) on 1 side and control force (0 g) on the contralateral side; group 2, light force (25 g) on 1 side and control force (0 g) on the contralateral side; group 3, light force (25 g) on 1 side and heavy force (225 g) on the contralateral side. After the experimental period, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed by using a microcomputed tomography scan x-ray system (SkyScan-1072, Skyscan, Aartselaar, Belgium) and specially designed software for direct volumetric measurements. RESULTS: The volume of the root resorption craters after intrusion was found to be directly proportional to the magnitude of the intrusive force applied. The results showed that the control group had fewer and smaller root resorption craters, the light force group had more and larger root resorption craters than the control group, and the heavy force group had the most and the largest root resorption craters of all groups. A trend of linear increase in the volume of the root resorption craters was observed from control to light to heavy groups, and these differences were statistically significant. The mean volumes of the resorption craters in the light and heavy force groups were 2 and 4 times greater than in the control groups, respectively. The mesial and distal surfaces had the greatest resorption volume, with no statistically significant difference between the 2 surfaces.

Adolescent↗
PubMed2005

Biochemistry of ginseng root tissues affected by rusty root symptoms.

Ginseng rusty root, a disorder of unknown cause (s), in which reddish-brown to orange-brown areas develop on the surface of field-grown roots, was studied at the cellular and biochemical levels. Using light microscopy, the affected areas were shown to comprise of the epidermis and underlying 6-8 cell layers of the cortical tissues. Rusty root areas ranged from small clusters of 3-4 cells to larger expanding areas of >80 cells. These cells appeared golden-brown and stained a bluish-green with Toluidine Blue indicating the presence of phenolic compounds. Energy-dispersive X-ray spectroscopy and atomic emission spectrometry of affected epidermal cells revealed a significant accumulation of Fe, Al, Si, Mg and other cations when compared to adjoining healthy cells. The concentrations of the six most common ginsenosides found in ginseng roots (Rg(1), Re, Rb(1), Rc, Rb(2), and Rd) were reduced by 40-50% in rusty root-affected epidermal and cortical tissues when compared to adjacent healthy tissues. Total phenolic compounds were increased by up to threefold in affected tissues and HPLC analysis revealed significantly higher levels of quercetin, cinnamic acid, vanillic acid, p-coumaric acid, benzoic acid, chlorogenic acid and catechin. In vitro phenolic-metal binding assays confirmed that phenolic compounds were able to sequester positively-charged metal ions, in particular Fe, to form a phenolic-metal ion complex. In ginseng callus cultures, accumulation of phenolic compounds was increased threefold within 12 h of treatment with chitosan (1%), and to a lesser extent by wounding. Specific defense enzymes, namely phenylalanine ammonia-lyase (PAL, E.C. 4. 3. 1. 5.), polyphenoloxidase (PPO, E.C. 1. 10. 3. 1.) and peroxidase (POD, E.C. 1. 11. 1. 7.), were also significantly enhanced in treated callus tissues and in rusty root tissues. On field-grown ginseng roots, application of chitosan induced symptoms similar to rusty root, whereas wounding and ethylene treatments did not. Based on these results, rusty root symptoms on ginseng are proposed to result from an induction of host defense responses, especially phenolic production, in epidermal and underlying cortical cells. This induction is likely due to attempted invasion by as-yet uncharacterized chitin-containing soil fungi, which were observed in many of the affected cells. Subsequent oxidation of phenolic compounds and sequestration of metal ions, in particular Fe, appear to be largely responsible for the symptoms observed.

Cations↗
PubMed2004

KNAT6 gene of Arabidopsis is expressed in roots and is required for correct lateral root formation.

As part of a programme to determine whether root development requires a pathway involving KNOTTED-like homeobox ( KNOX ) genes, we cloned the KNAT6 cDNA, a member of the KNOX gene family in Arabidopsis, from root tissue. The KNAT6 cDNA is represented by two isoforms, suggesting that the KNAT6 transcript is subject to alternative splicing. Promoter-reporter and RT-PCR analysis confirms expression of the KNAT6 gene in roots, and in particular in the phloem tissue close to the site of lateral root initiation, though not in the primary or lateral root meristem. The KNAT6 gene promoter activity is altered in pattern by treatment with exogenous auxin and in the rooty mutant background, with expression shifting distally in the root. In contrast, exogenous cytokinin suppresses KNAT6 promoter activity. KNAT6::GFP fusion protein is localized to the nucleus, consistent with the predicted function of KNAT6 as a transcription factor. Over-expression of the more abundant shorter isoform of the KNAT6 cDNA, but not of the less abundant longer form, leads to a lobed leaf phenotype, but no consistently aberrant root phenotype. Down-regulation of KNAT6 expression by RNA interference was associated with an increased total number of lateral roots. These data indicate a role for KNAT6 in modulating lateral root formation.

Amino Acid Sequence↗
PubMed2002

Lateral root formation is blocked by a gain-of-function mutation in the SOLITARY-ROOT/IAA14 gene of Arabidopsis.

Lateral root development is a post-embryonic organogenesis event that gives rise to most of the underground parts of higher plants. Auxin promotes lateral root formation, but the molecular mechanisms involved are still unknown. We have isolated a novel Arabidopsis mutant, solitary-root (slr), which has reduced sensitivity to auxin. This dominant slr-1 mutant completely lacks lateral roots, and this phenotype cannot be rescued by the application of exogenous auxin. Analysis with cell-cycle and cell-differentiation markers revealed that the slr-1 mutation blocks cell divisions of pericycle cells in lateral root initiation. The slr-1 mutant is also defective in root hair formation and in the gravitropic responses of its roots and hypocotyls. Map-based positional cloning and isolation of an intragenic suppressor mutant revealed that SLR encodes IAA14, a member of the Aux/IAA protein family. Green fluorescent protein-tagged mutant IAA14 protein was localized in the nucleus, and the gain-of-function slr-1/iaa14 mutation decreased auxin-inducible BA-GUS gene expression in the root, suggesting that SLR/IAA14 acts as a transcriptional repressor. These observations indicate that SLR/IAA14 is a key regulator in auxin-regulated growth and development, particularly in lateral root formation.

Amino Acid Sequence↗
PubMed1999

Endoxyloglucan transferase cDNA isolated from pea roots and its fluctuating expression in hydrotropically responding roots.

We isolated an endoxyloglucan transferase cDNA (Ps-EXGT1) from the roots of an agravitropic pea mutant, ageotropum. The putative product of the cDNA was 34.1 kDa and consisted of 293 amino acid residues. The predicted amino acid sequence was 75.1-88.6% identical to those of EXGT genes in other plants. The Ps-EXGT1 cDNA was strongly expressed in elongating roots and stems but not in either mature stems or young leaves. In roots, the transcription level of Ps-EXGT1 was most abundant in the rapidly growing region. When root elongation was inhibited by a water stress, Ps-EXGT1 transcription was repressed. The roots curved hydrotropically due to differential growth of the cortical cells in the elongation zone when the root cap was exposed to a gradient of water potential; the length of the cells on the side of lower water potential was much longer than those on the side of higher water potential. The expression pattern of Ps-EXGT1 in the hydrotropically responding roots fluctuated between the side of the higher water potential and that of the lower water potential in the elongation zone. In other words, the accumulation of Ps-EXGT1 mRNA was much greater on the side of lower water potential than on that of higher potential just prior to the commencement of positive hydrotropism. When the roots started to curve slightly away from the side of higher water potential causing a rhythmic oscillatory movement [Takano et al. (1995) Planta 197: 410], there was more transcription of Ps-EXGT1 on the side of higher water potential. These results suggest that the transcription of Ps-EXGT1 is involved in cell growth and that this regulation of transcription plays a role in the differential growth of hydrotropically responding roots.

Amino Acid Sequence↗
PubMed2003

Randomization of cortical microtubules in root epidermal cells induces root hair initiation in lettuce (Lactuca sativa L.) seedlings.

Root hair formation is induced when lettuce seedlings are transferred from liquid medium at pH 6.0 to fresh medium at pH 4.0. If seedlings are transferred to pH 6.0, no root hairs are formed. We investigated the role of microtubules in this low pH-induced root hair initiation in lettuce. At the hair-forming zone in root epidermal cells, microtubules were perpendicular to the longitudinal axis of the cell just after pre-culture. This arrangement became disordered as early as 5 min after transfer to pH 4.0, and became random by 30 min later. At pH 4.0, the randomization extended to the entire hair-forming zone of seedlings; at pH 6.0, however, randomization did not occur and transverse microtubules were maintained. When seedlings at pH 6.0 were treated with microtubule-depolymerizing drugs, root hairs were formed. In contrast, when a microtubule-stabilizing drug, taxol, was added to the medium, no root hairs formed, even at pH 4.0. These results suggest that the transverse cortical microtubules inhibit root hair formation, and that their destruction is necessary for initiation. Furthermore, the microfilament-disrupting drugs cytochalasin B and latrunculin B inhibited root hair initiation, suggesting that actin filaments are necessary for root hair initiation.

Bridged Bicyclo Compounds, Heterocyclic↗
PubMed2005

Double knockouts of phospholipases Dzeta1 and Dzeta2 in Arabidopsis affect root elongation during phosphate-limited growth but do not affect root hair patterning.

Root elongation and root hair formation are important in nutrient absorption. We found that two Arabidopsis (Arabidopsis thaliana) phospholipase Ds (PLDs), PLDzeta1 and PLDzeta2, were involved in root elongation during phosphate limitation. PLDzeta1 and PLDzeta2 are structurally different from the majority of plant PLDs by having phox and pleckstrin homology domains. Both PLDzetas were expressed more in roots than in other tissues. It was reported previously that inducible suppression or inducible overexpression of PLDzeta1 affected root hair patterning. However, gene knockouts of PLDzeta1, PLDzeta2, or the double knockout of PLDzeta1 and PLDzeta2 showed no effect on root hair formation. The expression of PLDzetas increased in response to phosphate limitation. The elongation of primary roots in PLDzeta1 and PLDzeta2 double knockout mutants was slower than that of wild type and single knockout mutants. The loss of PLDzeta2, but not PLDzeta1, led to a decreased accumulation of phosphatidic acid in roots under phosphate-limited conditions. These results indicate that PLDzeta1 and PLDzeta2 play a role in regulating root development in response to nutrient limitation.

Arabidopsis↗
PubMed1998

Characterization of LeMir, a root-knot nematode-induced gene in tomato with an encoded product secreted from the root.

A tomato gene that is induced early after infection of tomato (Lycopersicon esculentum Mill.) with root-knot nematodes (Meloidogyne javanica) encodes a protein with 54% amino acid identity to miraculin, a flavorless protein that causes sour substances to be perceived as sweet. This gene was therefore named LeMir (L. esculentum miraculin). Sequence similarity places the encoded protein in the soybean trypsin-inhibitor family (Kunitz). LeMir mRNA is found in root, hypocotyl, and flower tissues, with the highest expression in the root. Rapid induction of expression upon nematode infection is localized to root tips. In situ hybridization shows that LeMir is expressed constitutively in the root-cap and root-tip epidermis. The LeMir protein product (LeMir) was produced in the yeast Pichia pastoris for generation of antibodies. Western-blot analysis showed that LeMir expression is up-regulated by nematode infection and by wounding. LeMir is also expressed in tomato callus tissue. Immunoprint analysis revealed that LeMir is expressed throughout the seedling root, but that levels are highest at the root/shoot junction. Analysis of seedling root exudates revealed that LeMir is secreted from the root into the surrounding environment, suggesting that it may interact with soil-borne microorganisms.

Amino Acid Sequence↗
PubMed2001

Antisense expression of an Arabidopsis ran binding protein renders transgenic roots hypersensitive to auxin and alters auxin-induced root growth and development by arresting mitotic progress.

We cloned a cDNA encoding an Arabidopsis Ran binding protein, AtRanBP1c, and generated transgenic Arabidopsis expressing the antisense strand of the AtRanBP1c gene to understand the in vivo functions of the Ran/RanBP signal pathway. The transgenic plants showed enhanced primary root growth but suppressed growth of lateral roots. Auxin significantly increased lateral root initiation and inhibited primary root growth in the transformants at 10 pM, several orders of magnitude lower than required to induce these responses in wild-type roots. This induction was followed by a blockage of mitosis in both newly emerged lateral roots and in the primary root, ultimately resulting in the selective death of cells in the tips of both lateral and primary roots. Given the established role of Ran binding proteins in the transport of proteins into the nucleus, these findings are consistent with a model in which AtRanBP1c plays a key role in the nuclear delivery of proteins that suppress auxin action and that regulate mitotic progress in root tips.

Amino Acid Sequence↗
PubMed2005

Root canal preparation with Endo-Eze AET: changes in root canal shape assessed by micro-computed tomography.

AIM: To evaluate the relative performance of Endo-Eze Anatomic Endodontic Technology (AET) stainless steel instruments when shaping maxillary molar root canals in vitro. Methodology Extracted human maxillary molars were scanned, before and after root canal shaping with Endo-Eze AET, employing micro-computed tomography (muCT) at an isotropic resolution of 34 microm. Three-dimensional root canal models were reconstructed and evaluated for volume, surface area, 'thickness' (diameter), canal transportation and prepared surface. Preparation errors such as apical zips, perforations and fractured instruments were visually determined from those models. Means were contrasted using anova and Scheffé post-hoc tests. RESULTS: Volume and surface area increased significantly and similarly in mesiobuccal (mb), distobuccal (db) and palatal (p) canals and gross preparation errors (n = 17) were found. Mean root canal diameters, 5 mm coronal to the apex, increased from 0.31 to 0.52, 0.35 to 0.50 and 0.50 to 0.70 mm for mb, db and p canals, respectively. Mean canal transportation ranged from 0.15 to 0.29, 0.15 to 0.27 and 0.21 to 0.33 mm for apical, middle and coronal root canal levels, respectively, with highest values found for mb canals (P < 0.003). Root canals were significantly straightened during preparation (P < 0.002). CONCLUSIONS: In summary, Endo-Eze AET instruments shaped root canals in maxillary molars with substantial canal transportation, particularly in mesiobuccal root canals. Preparation with this instrument removed high volumes of dentine, even though apical preparation was size 30. Based on the current results, Endo-Eze AET cannot be recommended for the preparation of teeth with curved root canals.

Analysis of Variance↗
PubMed1992

Root canals in one-rooted maxillary second molars.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one-rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid-root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid-root and apically, the following variables: canal number, canal position, and canal cross-section. Mid-root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross-sections were non-circular, whereas 36.49% of the canals had a circular cross-section image. The non-circular canal cross-sections could more specifically be characterized as C-shaped, Y-shaped, hourglass-shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32% of the root canal cross-sections were non-circular, whereas 35.68% of the canals showed a circular cross-section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists.

Classification↗
PubMed1990

[Tooth movement of an impacted lower 2nd premolar in the root developmental stage--a follow-up radiographic observation on the root formation].

A 9 year old girl presented an impacted lower right 2nd premolar which not only was in horizontal position, but its crown was directed lingually. As a lower right 2nd premolar was in such a position that normal eruption was impossible, the deciduous predecessor was extracted at 9 years of age, and then sufficient space had been created for the lower right 2nd premolar to be erupted, and the eruption of it was observed for about 2 years. 2 years later, radiographic indication showed that no spontaneous eruption of a lower right 2nd premolar was to be expected. At 11 years of age, surgical exposure and traction of a lower right 2nd premolar was attempted. When the lower right 2nd premolar was upright, its root formation was in the 1st stage of root developmental stages according to Moorrees et al. Follow up radiographic observations on surgical exposure and traction of a lower right 2nd premolar 3 years later revealed the following results: 1. The root development went on to amount to about 90 percent of the root formation of the other tooth concerned without the curvature of the root. 2. Lamina dura and periodontal space were normal. The continued root formation was narrowing the root apex and the pulpal tissue of apical foramina was continuous with the periodontal space surrounding the root. 3. Bone deposition occurred at the alveolar crest and the latter was recontoured normally. The interdental and inter-radicular trabecula were good. As based on these results, normal development of the root of a lower right 2nd premolar with normal periodontium can be anticipated. Clinically, the lower right 2nd premolar had completely erupted and was in normal position on the arch and in occlusion. Color, vitality and mobility were normal. Periodontal support was good. The above-mentioned findings give support to the possibility that "early treatment" enables the impacted tooth to correct.

Bicuspid↗
PubMed2006

An assessment following root canal preparation by Er,Cr: YSGG laser irradiation in straight and curved roots, in vitro.

In the present study, the effectiveness of Er,Cr:YSGG laser in straight and curved root canal preparation was compared with that of the conventional canal preparation technique, in vitro. The degree of root curvature of 40 root canals was determined, and then 20 canals were prepared by an Er,Cr:YSGG laser of 2 W by using the crown-down technique, while the other 20 canals were shaped by K-file (control). The achievement degree of root canal preparation and debris score was investigated morphologically. The results indicated that straight root canals could be successfully prepared by Er,Cr:YSGG laser irradiation; a significant decrease of smear layer or debris was also recognized (P<0.01). However, canal preparation by laser device in curve root often leads to a ledge or zipped formation, perforation or over-instrumentation. The results demonstrated that further development in laser device and technique are required to ensure its success in root canal preparation, especially in curve root.

Dental Pulp Cavity↗
PubMed2001

Root canal treatment in mandibular canines with two roots: a report of two cases.

AIM: To highlight anatomical variation in the mandibular canine. SUMMARY: Two clinical case reports are presented to illustrate anatomical variation in the human mandibular canine. Endodontic treatment may sometimes fail because morphological features of the tooth adversely affect the treatment procedures. Many investigators have reported the anatomical variations associated with mandibular canines. Mandibular canines are recognized as usually having one root and one root canal in most cases, although approximately 15% may have two canals or sometimes two roots. This paper describes two clinical cases of mandibular canines with two roots and two canals. KEY LEARNING POINTS: Failure to control infection in the root canal system has an adverse impact on outcome. Clinicians should be aware of anatomical variations in the teeth they are managing, and should never assume that canal systems are simple. The majority of mandibular canines have one root and root canal, but 15% may have two canals, and a smaller number may have two distinct roots.

Cuspid↗
PubMed2003

Diagnosis and root canal treatment of a mandibular second premolar with three root canals.

AIM: To present a case of a mandibular second premolar with three root canals. SUMMARY: An accurate diagnosis of the morphology of the root canal system is a prerequisite for successful root canal treatment. A review of the literature reveals a low incidence of all types of premolars with three root canals. Diagnostic means such as preoperative radiographs and examination of the pulp chamber floor aid the location of root canal orifices. The diagnostic and therapeutic problems concerning premolars with unusual anatomy are described on the basis of a clinical example. A case report describes the successful treatment of a mandibular second premolar with three root canals. KEY LEARNING POINTS: Clinicians should be aware of unusual root canal anatomy in mandibular premolars. Radiographs exposed at two different horizontal angles and their careful interpretation facilitate the search of additional root canals. The use of magnification and additional lighting are recommended for the clinical examination of the pulpal floor.

Adult↗