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At least 415 records · Page 23Linked to original sources
PubMed1989

Traumatic lumbosacral nerve root meningoceles. The value of myelography, CT and MRI in the assessment of nerve root continuity.

A case of traumatic lumbar meningoceles at four levels in combination with total and partial nerve root avulsion and with preservation of a nerve root is reported. Several diagnostic imaging techniques (myelography, CT, myelo-CT and MRI) are compared and their value in demonstrating the continuity of the nerve roots is discussed. MRI could assess the continuity of a nerve root in a traumatic meningocele, not demonstrable by myelography or myelo-CT. The combination of myelography, myelo-CT and MRI is likely to provide a complete diagnostic evaluation of nerve root lesions.

Adult↗
PubMed1994

Immunoelectron microscopic localization of E-cadherin in dorsal root ganglia, dorsal root and dorsal horn of postnatal mice.

Sensory neurons and associated glial cells are known to express the cell-cell adhesion molecule E-cadherin. The cellular and subcellular localization of this molecule in the dorsal root ganglion, dorsal root, and spinal cord of postnatal mice was studied by the pre-embedding immunoelectron microscopic labelling technique. In the dorsal root and the superficial layer of the dorsal horn, a subset of fasciculating unmyelinated axons expressed E-cadherin at their axon-axon contacts at all ages studied, and these axons were clustered together and segregated from E-cadherin-negative axons. In contrast, pre-myelinating large-diameter axons in P2 mice as well as myelinated axons in mice from P14 to adulthood were E-cadherin-negative. Glial cells also expressed E-cadherin: In the dorsal root ganglia, all of the satellite cells expressed E-cadherin at contact sites with neurons, other satellite cells, and basal lamina, at all ages studied. In dorsal roots from P14 to adulthood, myelin-forming Schwann cells expressed E-cadherin at the outer mesaxons and the contact sites with basal lamina. Non-myelin-forming Schwann cells occasionally stained for this molecule at contact sites with the plasma membrane of E-cadherin-positive axons and at other sites. These results strongly suggest that E-cadherin plays an important role in the selective fasciculation of a particular subset of unmyelinated sensory fibres, and also in glial cell contacts.

Animals↗
PubMed1989

Biomechanics of the lumbar spinal nerve roots and the first sacral root within the intervertebral foramina.

This study consists of 3 sections: a descriptive study of the intervertebral foramen by dissection, supplemented by millimetric sections made with the cine-microabrasive apparatus (patented) on 12 specimens frozen with liquid nitrogen; a study of the attachments of the roots made during manipulations testing the resistance to avulsion of the rootlets, the roots, the dural sheath and the fibrous expansions at the periphery of the intervertebral foramen; and a study of the mobility of the roots in the foramina during movements effected within and outside the spine. We concluded that the classical description of an intervertebral foramen as occluded by a taut membrane like a drum-head is false as only perforated expansions attach the root to the foramen. Further, the points for attachment of the roots are the dura mater and the fibrous expansion passing from the foramen to the sheath of the spinal n. Finally, from the aspect of mobility, there are 2 distinct compartments and movements in one are not perceived in the other compartment if the attachments are unbroken. These attachments are a barrier interposed between the two compartments.

Biomechanical Phenomena↗
PubMed1997

Neuropathology and blood flow of nerve, spinal roots and dorsal root ganglia in longstanding diabetic rats.

Vascular perfusion and neuropathologic evaluation of the lumbar spinal roots and dorsal root ganglia (DRG) were studied in rats with longstanding (duration 12-15 months) streptozotocin-induced diabetes and age- and sex-matched control rats. We also undertook nerve conduction studies including F-wave recordings and measured blood flow in sciatic nerve, DRG, and superior cervical ganglion (SCG). Light microscopically, changes of the myelin sheath in the dorsal and ventral roots and vacuolated cells in the DRG were the major findings, being significantly higher in diabetic rats than in control rats. The effects of the diabetic state on myelin splitting were greater in the dorsal than ventral roots. Electron microscopic studies revealed a gradation of changes in myelin from mild separation to severe ballooning of myelin with relative axonal sparing. DRG cells showed vacuoles of all sizes with cristae-like residues, suggestive of mitochondria. These findings suggest that diabetes mellitus has a dual effect: it accelerates the normal age-related degenerative changes in the spinal roots and DRG, and it also has a selective effect on the sensory neuron. Nerve conduction studies showed markedly reduced conduction velocities in the distal nerve segments and prolonged F-wave latency and proximal conduction time despite the shorter conduction pathway in diabetic rats. Blood flow, which was measured using iodo[14C]antipyrine autoradiography, was significantly reduced in the sciatic nerves, DRG, and SCG of diabetic rats. We suggest that the combination of hyperglycemia and ischemia results in oxidative-stress and a predominantly sensory neuropathy.

Animals↗
PubMed1997

A stereological study of dorsal root ganglion cells and nerve root fibers from rats treated with inorganic mercury.

Unbiased stereological methods have been used to quantify the effects of inorganic mercury on the morphology of the fifth lumbar dorsal root ganglion cells and nerve root fibers. Adult male Wistar rats were treated with intraperitoneal injections of mercuric chloride (0.15 mg daily) for 30 days. The total numbers and mean volumes of A- and B-cell perikarya were estimated using the optical fractionator and the vertical rotator techniques. The total numbers of myelinated axons in the ventral and the dorsal roots were estimated with the two-dimensional fractionator technique and the areas of axon and myelin were estimated using the two-dimensional nucleator technique. No differences were found for any parameters in experimental and control animals, indicating that inorganic mercury intoxication alters neither the numbers or sizes of dorsal root ganglion cells and nerve root fibers nor the amount of myelin associated with the nerve fibers.

Animals↗
PubMed2002

Saprobic characteristics of three fungal taxa from ericalean roots and their association with the roots of Rhododendron groenlandicum and Picea mariana in culture.

Simultaneous associations among ectotrophic and ericoid mycorrhizal hosts and their mycorrhizal fungi are expected in boreal bogs where ericaceous shrubs and conifers coexist rooted in an organic matrix dominated by Sphagnum mosses. We were thus prompted to examine, in vitro, the abilities of three ericoid mycorrhizal fungi [ Hymenoscyphus ericae, Oidiodendron maius, and Variable White Taxon (VWT)] to associate with Picea mariana (Pinaceae), with both P. mariana and Rhododendron groenlandicum (Ericaceae) simultaneously, and to decompose Sphagnum fuscum. Hymenoscyphus ericae and VWT developed an intracellular association with roots of P. mariana and with roots of R. groenlandicum. Two strains of O. maius did not form typical infection units in R. groenlandicum, nor did they colonize the root cells of P. mariana. Mass losses incurred by sterilized S. fuscum plants inoculated with these three taxa indicated that O. maius could be more efficient as a free-living saprophyte on this material than either H. ericae or VWT and may in part explain why atypical associations with the roots of ericaceous hosts were formed.

Ascomycota↗
PubMed1979

Studies of human and bovine spinal nerve roots and the outgrowth of CNS tissues into the nerve root entry zone.

The outpouching of CNS tissues into the entering spinal nerve roots was documented by light and electron microscopy of human and bovine tissues. Astrocytic processes containing large bundles of glial filaments were very prominent in the nerve entry zone and extended for short distances into the adjacent endoneurium of the spinal nerve roots. Antiserum raised to glial acidic fibrillary (GFA) protein stained these glial elements, thereby characterizing the dome-shaped evaginations of CNS tissues into the nerve root entry zones. Antisera to CNS basic protein showed enhanced staining in the nerve entry zone. Analyses of nerve proteins by SDS gel electrophoresis disclosed a prominent 49,000 MW protein in the bovine and human nerve root entry zone. This protein was also prominent in spinal cord white matter, but was not seen in nerve roots which were not admixed with glial tissues. This finding supported the view that a 49,000 MW protein is a glial filaments but is not a component of bovine or human neurofilaments.

Animals↗
PubMed2006

Comparison of the sealing of Resilon, Pro Root MTA, and Super-EBA as root-end filling materials: a bacterial leakage study.

The purpose of this in vitro study was to compare the root-end sealing of the Resilon/Epiphany system (RES) to Pro Root MTA and Super-EBA using a bacterial leakage system. Fifty-five extracted teeth were instrumented and root-ends were resected and ultrasonically prepared. Test materials were placed in the root-end preparations; Streptococcus salivarius was introduced coronally and the apical 4 mm were immersed in BHI culture medium with phenol red indicator. Bacterial leakage was monitored every 24 h for 4 wk. All positive controls leaked within 24 h; none of the negative controls leaked. Based on chi2 analysis (p < 0.05), RES and MTA leaked significantly less than Super-EBA. There was no statistical difference between RES and MTA. RES may be a viable option as a root-end filling material with good surgical isolation.

Aluminum Compounds↗
PubMed2005

The effect of root cooling on hormone content, leaf conductance and root hydraulic conductivity of durum wheat seedlings (Triticum durum L.).

Root cooling of 7-day-old wheat seedlings decreased root hydraulic conductivity causing a gradual loss of relative water content during 45 min (RWC). Subsequently (in 60 min), RWC became partially restored due to a decrease in transpiration linked to lower stomatal conductivity. The decrease in stomatal conductivity cannot be attributed to ABA-induced stomatal closure, since no increase in ABA content in the leaves or in the concentration in xylem sap or delivery of ABA from roots was found. However, decreased stomatal conductance was associated with a sharp decline in the content of cytokinins in shoots that was registered shortly after the start of root cooling and linked to increases in the activity of cytokinin-oxidase. This decrease in shoot cytokinin content may have been responsible for closing stomata, since this hormone is known to maintain stomatal opening when applied to plants. In support of this, pre-treatment with synthetic cytokinin benzyladenine was found to increase transpiration of wheat seedlings with cooled roots and bring about visible loss of turgor and wilting.

Abscisic Acid↗
PubMed2005

Effect of acute nerve root compression on endoneurial fluid pressure and blood flow in rat dorsal root ganglia.

The objective of the current study was to test the hypothesis that crush injury to nerve root increases endoneurial fluid pressure (EFP) and decreases blood flow in the associated dorsal root ganglion (DRG). A total of 21 adult, female Sprague-Dawley rats had their left L5 nerve root and DRG exposed. The L5 nerve root was clamped for 2 s with a vascular suture clip just proximal to the DRG (compression group). Sham-operated animals without compression were used for control (control group). EFP was recorded with a servo-null micropipette system using a glass micropipette with tip diameter of 4 mum before and after 3 h of treatment. After the final measurement of EFP, DRG was excised and processed for histology. Blood flow in the DRG was continuously monitored by laser Doppler flow meter for 3 h. Three hours after treatment, EFP was 4.7+/-2.7 cm H(2)O in the compression group and 2.2+/-1.2 cm H(2)O in the control group (P<0.05). Edema was the principal pathologic findings seen consistently in the DRG from animals in the compression group. Blood flow in the compression group was reduced 10 min after compression. This reduction was statistically significant compared with that of the control (P<0.01). An acute compression to the nerve root increased endoneurial edema, increased EFP in the associated DRG, and reduced DRG blood flow. This combination of increased EFP and decreased blood flow in the DRG may result in neuronal ischemia and sensory dysfunction. These acute pathophysiologic changes may thus have a role in the pathogenesis of low back pain and sciatica due to disc herniation and spinal canal stenosis.

Acute Disease↗
PubMed1989

Vertical root fractures in curved roots under simulated clinical conditions.

The purpose of this study was to determine the incidence of vertical root fractures in the mesial roots of extracted human mandibular molars that were endodontically prepared by hand or ultrasonic instrumentation and obturated with laterally condensed gutta-percha and sealer using finger and hand spreaders. One-hundred twenty mesiofacial canals were prepared by hand or ultrasonic instrumentation. After placing the teeth in a simulated alveolus, they were obturated by laterally condensing gutta-percha and sealer with B-finger or D11T hand spreaders. Teeth were obturated using forces in the range of 1 to 3 kg or 4.5 to 7.5 kg. Three teeth obturated with the D11T hand spreader using 7.0 to 7.3 kg of force demonstrated vertical root fractures. The results suggest that in vitro the range of forces reported as most commonly used by endodontists to laterally condense gutta-percha (1.0 to 3.0 kg) and those of a higher magnitude up to 4.9 kg are safe and will not result in vertical root fractures of mesial roots of mandibular molars.

Dental Pulp Cavity↗
PubMed1998

Effect of power settings versus temperature change at the root surface when using multiple fiber sizes with a Holmium YAG laser while enlarging a root canal.

The aim of this study was to determine if there is an increase in temperature at the root surface as the canal is enlarged when using a Holmium:YAG laser. An increase might be expected because, as the canal is enlarged, there is less dentin between the canal walls and the outer cementum surface of the root to absorb the heat. Sixty single-rooted human teeth were randomly assigned to 1 of 3 groups according to laser power settings: 0.50, 0.75, and 1.00 W. Each tooth in each power group was subjected to lasing using fiber sizes of 140, 245, 355, and 410 microns. The dependent variables in these analyses included: (a) change in temperature, measured with T-type thermocouples placed 2 mm from the coronal and apical ends of the root; (b) depth of laser in the tooth; (c) depth that a conventional fiber could be inserted after lasing; and (d) tooth physical dimensions. ANOVA for coronal temperature showed no interaction between fibers and power settings. Repeated-measures ANOVA for apical temperature showed a significant difference between fibers, but not between power settings. No interaction between fibers and power settings was observed. For the depth of tooth during lasing (how far the fiberoptic guide penetrated into the tooth), no interaction between fibers and power settings was observed. Pairwise contrasts revealed that all fibers were different from one another, with depth decreasing as fiber size increased. Depth files could be inserted that showed the depth significantly decreased as file size increased from 50 through 70. ANOVAs illustrated that there were no significant differences between power settings for any of the five tooth physical dimensions. All temperature differences observed apically and coronally were between 0 degree to 10 degrees C, with the majority (> 98%) being between 0 degree to 5 degrees C. After lasing with the 410-micron fiber, the root canals were widened to at least 45 or 50 K-files (450 or 500 microns). However, by using a 410-micron fiber, the laser did not seem to widen the canal beyond a 500-micron diameter.

Analysis of Variance↗
PubMed1999

Temperature elevation on the root surface during Nd:YAG laser irradiation in the root canal.

Nd:YAG lasers have been suggested as a potential tool in endodontic therapy because of their sterilizing and sealing effects on the dentinal tubules. However, the generation of heat in the root canal by laser irradiation may produce potentially harmful effects on adjacent tissues. The purpose of this study was to evaluate the temperature elevation on the root surface when Nd:YAG laser was irradiated in the root canal. The apical third area of 90 single-rooted teeth were irradiated with normal pulsed Nd:YAG laser (50, 80, 100, 150, and 200 mJ/pulse; 20, 25, and 30 pulses/s). The temperature elevation was measured and recorded on the root surface simultaneously. The temperature elevation did not exceed 10 degrees C only when the laser energy output was below 100 mJ/pulse and under 20 pulses/s.

Body Temperature↗
PubMed1990

Influence of root development and root anatomy on the occurrence of periodontal damage during removal of third molars for transplantation: a histometric study.

The purpose of this study was to determine the influence of root development and root anatomy on surgically induced periodontal damage to third molars resulting from removal prior to transplantation. Thirty impacted third molars were removed by a careful technique, whereas another 30 were removed by the usual vestibular osteotomy and served as controls. Periodontal damage was histometrically evaluated on serial cross sections of the whole root and classified according to five categories describing the extent of damage to periodontal fibers, cementoblasts, and the cementum layer. The results showed more extensive damage to the periodontal membrane in the more mature stages of root development. A statistically significant influence of root anatomy on the occurrence of periodontal damage was not found.

Dental Cementum↗
PubMed1994

Periodontal conditions after facial root tipping and palatal root torque of incisors.

UNLABELLED: The maxilla of a deceased 19-year-old young woman who had been treated with a fixed appliance was removed during autopsy. The sagittal movements of the incisors could be reconstructed by using the treatment records, which were also at our disposal. The anterior segment of the specimen was prepared histologically in the sagittal plane and stained with toluidine blue. RESULTS: The tooth movements were executed in two phases: an uncontrolled tipping (root movement to vestibular) was followed by palatinal root torque. The histologic changes, induced by the palatinal root torque were (1) root resorption with apical slope from facioapical to orocoronal, and (2) pronounced subperiosteal bone apposition (palatinal) with partial protrusion of the cortical plate thinning toward coronal. No osseous perforations occurred. The extent and the localization of root resorptions were not verified in the orthoradial x-ray film of the specimen.

Adult↗
PubMed2003

Root-specific CLE19 overexpression and the sol1/2 suppressors implicate a CLV-like pathway in the control of Arabidopsis root meristem maintenance.

In the Arabidopsis shoot apical meristem, an organizing center signals in a non-cell-autonomous manner to specify the overlying stem cells. Stem cells express the small, secreted protein CLAVATA3 (CLV3; ) that activates the CLV1-CLV2 receptor complex, which negatively controls the size of the organizing center. Consistently, CLV3 overexpression restricts shoot meristem size. The root meristem also contains a stem cell organizer, and here we show that localized overexpression in roots of CLE19, encoding a CLV3 homolog, restricts the size of the root meristem. This suggests that CLE19 acts by overactivating an endogenous CLV-like pathway involved in root meristem maintenance. Surprisingly, CLE19 restricts meristem size without directly interfering with organizer and stem cell specification. We isolated mutations in two loci, SOL1 and SOL2, which suppress the CLE19 overexpression phenotype. sol2 plants display floral phenotypes reminiscent of clv weak alleles; these phenotypes suggest that components of a CLV pathway are shared in roots and shoots. SOL1 encodes a putative Zn(2+)-carboxypeptidase, which may be involved in ligand processing.

Amino Acid Sequence↗
PubMed1998

The significance of locating and filling the canal isthmus in multiple root canal systems. A scanning electron microscopy study of the mesiobuccal root of maxillary first permanent molars.

The mesiobuccal (MB) roots of 50 randomly selected maxillary first permanent molars were examined to evaluate the different configurations of canal isthmus and their incidences. Sections of the roots at 3.4, and 5 mm from the apex were prepared, acid etched, washed and dried. The apical side of each section was sputter coated with gold, examined by a Hitachi S-2500 scanning electron microscope and photographed. 36% of the mesiobuccal roots had one canal, whereas 64% had two canals. In the roots with two canals 31.25% contained either a complete isthmus, or accessory canals between the two main canals 31.25% showed partial isthmus formation. The significance of the different configurations is discussed. Our present findings indicate that the mesiobuccal roots of maxillary first permanent molars exhibit complex anatomy. Prudent judgement is essential in the canal isthmus preparation so that operators must provide meticulous skill and care to the patients.

Dental Pulp Cavity↗
PubMed2006

[Effects of exogenous phytohormones on hairy root growth and biosynthesis of anthraquinones in the hairy root culture of Polygonum multiflorum].

The effects of exogenous phytohormones on hairy root growth and biosynthesis of anthraquinones in the hairy root cultures of Polygonum multiflorum Thunb. were studied. The results showed that the 2,4-D, NAA and 6-BA all have obvious effects on the growth of hairy root cultures and the biosynthesis of anthraquinones. The growth of hairy root and biosynthesis of anthraquinones were strongly restrained by 2,4-D. However, NAA and 6-BA of appropriate concentration were favourable to hairy root growth and anthraquinones production.

2,4-Dichlorophenoxyacetic Acid↗