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At least 145 records · Page 8Linked to original sources
PubMed1996

Changes in responses of wide dynamic range neurons in the spinal dorsal horn after dorsal root or dorsal root ganglion compression.

STUDY DESIGN: The electrophysiologic responses of wide dynamic range neurons in the spinal dorsal horn by compression of the dorsal root or of the dorsal root ganglion were investigated. OBJECTIVES: This study identified differences between the compression of the dorsal root against the compression of the dorsal root ganglion by examining the responses of wide dynamic range neurons. SUMMARY OF BACKGROUND DATA: The wide dynamic range neurons studied were known to be excited by primary afferent fibers, not only combined A delta and C-nociceptive fibers but also low threshold mechanoreceptive A beta fibers and A delta fibers of down hairs. Thus, the wide dynamic range neurons are classified as nociceptive neurons. METHODS: Extracellular activities of 32 wide dynamic range neurons were recorded from the laminae 4-6 of the seventh lumbar cord in anesthetized cats. A microvessel clip (40 g) was applied to compress the dorsal root or the dorsal root ganglion. RESULTS: Dorsal root compression produced only an initial burst (about 10-40 seconds). Prolonged repetitive firings were rarely maintained. In contrast, dorsal root ganglion compression resulted in a maintained repetitive firing throughout the period of compression. After release of compression of the dorsal root and the dorsal root ganglion, responses to brushing were facilitated, and the low threshold center of the receptive field expanded. CONCLUSIONS: These findings are consistent with the previous report that the radicular pain associated with a herniated intervertebral disc initially results from compression of the dorsal root ganglion.

Animals↗
PubMed1998

Neuromonitoring of an experimental model of clip compression on the spinal nerve root to characterize acute nerve root injury.

OBJECTIVES: To evaluate the sensitivity of an electro-monitoring method in acute nerve root injury, and to determine a proposed criterion for irreversible electrophysiologic degradation. STUDY DESIGN: Acute nerve root injury was induced by a clip compression model in rabbits, mimicking nerve root injury by a transpedicular screw. A common neuromonitoring technique, spinal somatosensory-evoked potential, was used to study the electrophysiologic change during the procedure. SUMMARY OF BACKGROUND DATA: With the advent of the transpedicular screw system, increased risk of injury to the spinal root because of the passage of screws is not unexpected. Although both an experimental model and a clinical application in intraoperative neuromonitoring of spinal cord function have been established, the value of neuromonitoring of an acute spinal root injury remains obscure. Several neurophysiologic surveillance techniques have been used successfully to monitor the potential injury to the spinal cord during orthopedic procedures around the spinal cord and spinal column. Spinal somatosensory-evoked potential, which has the advantages of high amplitude and quick recording time, is used to detect nerve root impairment during the insertion of transpedicular screws. METHODS: Experimental acute nerve root injury was induced in rabbits by direct hemostatic clip compression on the nerve root (S1) during different time intervals. Spinal somatosensory-evoked potential elicited by stimulating the sciatic nerve and recorded from a needle electrode at the L6-L7 interspinous ligament was monitored immediately before and after compression. RESULTS: Spinal somatosensory-evoked potential is sensitive enough to detect the compromise of a single nerve root and that a decrease in the amplitude is the most reliable and sensitive sign. With this model, there was a statistically significant correlation between the compression time and reduction of amplitude and delay of latency. The criterion for irreversible electrophysiologic change was an amplitude loss of more than 20% and a delay in latency immediately after nerve root compression. CONCLUSIONS: It was concluded that spinal somatosensory-evoked potential can provide immediate feedback of nerve root injury and should be considered for use during the dynamic phase of transpedicular screw insertion.

Animals↗
PubMed2005

SEM analysis of the integrity of resected root apices of cadaver and extracted teeth after ultrasonic root-end preparation at different intensities.

AIM: To compare the integrity of root apices of cadaver and extracted teeth after resection, ultrasonic root-end cavity preparation at medium and low ultrasonic power settings and retrieval. METHODOLOGY: Root canal treatment, perpendicular root-end resection and root-end preparation were performed on single-rooted anterior and premolar teeth (49 teeth in situ in maxillary and mandibular jaws from cadavers and 45 extracted teeth). Apical root-end cavities were prepared with the S12/90 degrees D tip and the Suni-Max ultrasonic unit (Satelec, Merignac, France) at the intensity prescribed by the manufacturer (power 7 at power mode S) (34 cadaver teeth, 30 extracted teeth) and at a lower intensity (power 4 at power mode S) (15 cadaver teeth, 15 extracted teeth). After ultrasonic preparation the cadaver teeth were retrieved from the jaws. Exaflex impressions (GC Corporation, Tokyo, Japan) were made of the root apices after resection, root-end preparation and retrieval. These impressions were processed for SEM analysis, and the recordings evaluated for cracks and marginal chipping. RESULTS: In general, extracted teeth showed significantly more cracks and chipping than cadaver teeth. Lowering the ultrasonic power from medium to low intensity resulted in equal scores for cracks on extracted teeth and for chipping on cadaver teeth, in higher scores for cracks on cadavers and in lower scores for chipping on extracted teeth. Complete cracks and cracks originating from the root surface occurred only in extracted teeth. CONCLUSIONS: The number of cracks and degree of chipping caused by ultrasonic root-end preparation was higher on extracted teeth than on cadaver teeth. Lowering the ultrasonic power from medium to low intensity cannot be recommended as it resulted in more cracks and equal chipping on cadaver teeth. Investigation of techniques and materials should be conducted in situ and not on extracted teeth.

Apicoectomy↗
PubMed2005

The occurrence of dauciform roots amongst Western Australian reeds, rushes and sedges, and the impact of phosphorus supply on dauciform-root development in Schoenus unispiculatus (Cyperaceae).

* The incidence of species that develop specialised 'dauciform' lateral roots, which are hypothesised to be important for phosphorus (P) acquisition, is uncertain. We investigated their occurrence in Australian reed, rush and sedge species, grown at low P concentration in nutrient solution, and studied the response of Schoenus unispiculatus (Cyperaceae) to a range of P concentrations. * We assessed the fraction of root biomass invested in dauciform roots, their respiration and net P-uptake rate, and the P status of roots and leaves. * Dauciform-root development occurred only in particular genera of Cyperaceae when grown at low P supply. Increased P supply was associated with increased growth of S. unispiculatus and increased leaf [P]. Dauciform-root growth was reduced by increased P supply, and reduced P uptake co-occurred with the complete suppression of dauciform roots. * The P-induced suppression of dauciform roots in Cyperaceae is similar to that observed for proteoid roots in members of Proteaceae and Lupinus albus. The response of dauciform roots to altered P supply and their absence from root systems of some sedge species are discussed in terms of managed and natural systems.

Cyperaceae↗
PubMed2006

Fine-root turnover patterns and their relationship to root diameter and soil depth in a 14C-labeled hardwood forest.

Characterization of turnover times of fine roots is essential to understanding patterns of carbon allocation in plants and describing forest C cycling. We used the rate of decline in the ratio of 14C to 12C in a mature hardwood forest, enriched by an inadvertent 14C pulse, to investigate fine-root turnover and its relationship with fine-root diameter and soil depth. Biomass and Delta14C values were determined for fine roots collected during three consecutive winters from four sites, by depth, diameter size classes (< 0.5 or 0.5-2 mm), and live-or-dead status. Live-root pools retained significant 14C enrichment over 3 yr, demonstrating a mean turnover time on the order of years. However, elevated Delta14C values in dead-root pools within 18 months of the pulse indicated an additional component of live roots with short turnover times (months). Our results challenge assumptions of a single live fine-root pool with a unimodal and normal age distribution. Live fine roots < 0.5 mm and those near the surface, especially those in the O horizon, had more rapid turnover than 0.5-2 mm roots and deeper roots, respectively.

Biomass↗
PubMed1982

Effect of root surface alterations on periodontal healing. II. Citric acid treatment of the denuded root.

A companion study reported that new connective tissue attachment did not occur to a surgically denuded root surface when transplanted into a normal periodontium. It was the purpose of this study to evaluate periodontal healing adjacent to a citric acid treated denuded root surface. In four squirrel monkeys, 12 teeth were extracted and reimplanted after surgical denudation and citric acid conditioning of the coronal root surface. The study design provided three teeth for histologic analysis at 1, 3, 7 and 21 days after reimplantation. One and 3 days after reimplantation a zone of fibrin containing inflammatory cells and erythrocytes was interposed between the root surface and remaining periodontal fibers. The fibrin network appeared to be attached to the root surface by arcade-like formations. The apical termination of the epithelium was located at the coronal extent of the fibrin zone. Granulation tissue and new fibers were aggregating along and perpendicular to the root surface at 7 days, and new connective tissue attachment had been established at 21 days. Extensive root resorption was present along the intra-alveolar part of the root surface. Epithelium had not migrated apically along the denuded root surfaces. The results indicated that citric acid treatment of denuded root surfaces resulted in new connective tissue attachment, and the response appeared to be dependent upon early establishment of fibrin linkage with the root surface.

Animals↗
PubMed1987

The concentration of lipopolysaccharide on individual root surfaces at varying times following in vivo root planing.

Material with endotoxin activity has been detected in extracts prepared from pooled, periodontally involved teeth, and it has been shown that root planing in vivo reduces the level of such material. However, questions concerning the concentration of endotoxin on the diseased surfaces of individual teeth and questions concerning how rapidly individual root planed tooth surfaces retoxify in vivo have not been addressed previously. Citric acid extracts were prepared from individual, periodontally diseased teeth that had been extracted either from the oral cavity without prior root planing or at varying times up to 12 weeks following root planing. Using a chromogenic Limulus Amebocyte Lysate (LAL) assay, we were able to quantitate the amount of endotoxin associated with diseased root surfaces of individual teeth. We concluded that the extracted material contained endotoxin since it activated LAL and since the LAL-activation was heat-stable, acid-stable and neutralizeable by polymyxin B. The levels of endotoxin found on the root surfaces of these individual, periodontally involved teeth at varying times following in vivo root planing support the following conclusions: the concentration of endotoxin present on diseased root surfaces is markedly reduced, but not eliminated, by in vivo root planing, significant retoxification of root planed surfaces occurs within a relatively short time period after root planing and biological responses to such toxification conceivably may lead to subsequent phases having reduced levels of endotoxin.

Adult↗
PubMed1994

Root length, crown height, and root morphology in Turner syndrome.

Root length, crown height, and root morphology were studied on intraoral and panoramic radiographs in 33 Turner syndrome patients aged 7.0-16.7 years, subdivided on the basis of karyotype. Thirty-three normal girls aged 10.2-16.4 years served as controls. In the 45X patients and, with the exception of a few teeth, also in the isochromosome and mosaic karyotypes, root length and crown height of incisors, canines, and premolars were significantly reduced. Some teeth showed altered crown-root proportions. Maxillary first premolars showed a significantly increased number of two-rooted and three-rooted variants. Mandibular premolars and molars had a complex root morphology, and a classification system was established including four premolar and six molar root types. Premolars had a significantly increased number of root components. Some of the variants, such as a molar-like second premolar, are apparently specific for these patients. On several first molars a radix entomolaris was identified. Two separate mesial and one or two separate distal roots were also frequently seen. Our investigation demonstrates that X-chromosome deficiency influences root formation.

Adolescent↗
PubMed1996

Cytochemical assay for differential respiratory activity in roots and root hairs.

The study of the underground parts of plants is often difficult, and as a result roots are often treated as homogeneous physiological entities with respect to root respiration. In this study we demonstrate a partitioning of respiration within root tissues using nitro blue tetrazolium staining and an incident light optical system that permits detailed observations of intact roots. The assay is rapid and easy to perform, and reveals that respiratory activity in roots is not uniform in space and time. The results show that root hairs in particular may be regions of enhanced respiratory activity in some species or in certain developmental or physiological states. This fact has important implications for the role of root hairs in the overall respiratory budget of roots and the energetics of nutrient assimilation. The results suggest that root respiration studies should consider differential respiratory activities of root cell types within roots.

Adenosine Triphosphate↗
PubMed1997

Tissue response to potential root-end filling materials in infected root canals.

The tissue responses to two potential root-end filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide-eugenol cement (Kalzinol) were compared with that to amalgam. In 27 premolar teeth of beagle dogs (54 roots), a collection of endodontic pathogenic bacteria was first inoculated into the root canals to induce periapical lesions. On each root, an apicectomy was performed and root-end cavities prepared to receive fillings of each material. The teeth and surrounding jaw were removed after 8 weeks (24 roots) and 4 weeks (30 roots); and they were prepared for histological examination. The tissue response to amalgam fillings after 4 and 8 weeks was marked by moderate or severe inflammation on all roots, and extended > 0.5 mm in 10 out of 18 roots. In contrast, after 8 weeks, the majority of roots filled with Kalzinol showed little or moderate inflammation while the tissue response to Vitrebond was the best of the three materials, and was also less extensive. After 4 weeks, the overall best tissue response was with Kalzinol, followed closely by Vitrebond. The differences between materials for both time periods with either none or few inflammatory cells when compared with that with either moderate or severe inflammation were statistically significant (P < 0.01). Similarly, the differences between materials for both time periods with no inflammation or inflammation extending < 0.2 mm when compared with that with inflammation extending > 0.2 mm (< or = 0.5 mm or > 0.5 mm) were statistically significant (P < 0.01). Both Vitrebond and Kalzinol have potential as root-end filling materials as the tissue response was considerably more favourable than that to amalgam.

Animals↗
PubMed2006

[Effects of soil root-growing space on root physiological characteristics and grain yield of sorghum].

In this paper, soil culture was conducted on the Experimental Farm of Shanxi Agricultural University, with the sorghum planted in cylindrical nylon bags to confine the space of root growth but allow the pass-through of water and nutrients, aimed to study the effects of soil root-growing space on the root physiological characteristics and grain yield of sorghum. The results showed that the confinement of root growth space decreased the plant height, leaf area, SOD and POD activities in flag leaf, total root length, root absorbing area, dry weights of root and aboveground part, nutrient uptake and grain yield, but increased the activity of root and its active absorbing area. Fertilization stimulated the root growth under space stress, increased the activity of root and its absorbing area, promoted nutrient uptake, and thus, increased grain yield while decreased the detrimental effects derived from the confine of root growth space.

Biomass↗
PubMed2002

The effect of two different root canal sealers and smear layer on resistance to root fracture.

The purpose of this in vitro study was to test the effect of Ketac-Endo (KE) and AH 26 on resistance to root fracture and also to evaluate the effect of smear layer. Seventy-two human maxillary canine teeth were randomly divided into six groups (n = 12) and were prepared using six different methods: group 1: KE, without smear layer (smear -); group 2: KE, with smear layer (smear +); group 3: AH 26, smear (-); group 4: AH 26, smear (+); group 5 (negative control): nonprepared; group 6 (positive control): prepared but unfilled. After storing 1 week in 100% humidity at 37 degrees C, the coronal lingual walls and root canal spaces were lowered 2 mm below the buccal walls of the roots. The samples were placed into acrylic resin blocks so that 10 mm of buccal roots were exposed and were placed in a specially designed steel pad at an angle of 15 degrees to the long axis of the root. A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred. The force required to fracture each tooth was recorded as kg and statistically analyzed using one-way analysis of variance and Duncan tests. The results indicated that instrumentation of the root canals significantly weakened the tooth structure to fracture (p < 0.05). The canals obturated with either sealer were significantly stronger than roots whose canals were instrumented but not obturated (p < 0.05), and there was no difference between the sealers. The presence or absence of the smear layer did not cause any significant effect on the root fracture resistance of the teeth (p > 0.05).

Analysis of Variance↗
PubMed2006

Lateral root bridging as a strategy to enhance L-DOPA production in Stizolobium hassjoo hairy root cultures by using a mesh hindrance mist trickling bioreactor.

Stizolobium hassjoo hairy roots exhibited a lateral root bridging behavior, enabling not only root dry weight but enhancement of intracellular L-DOPA content. When a single root tip was exerted a proper hindrance, the primary root growth was inhibited while lateral roots were profusely induced. The hindrance-induced lateral roots from individual primary root could bridge together under appropriate inoculation densities, leading to high density hairy root cultures producing secondary metabolites. In the present paper, a novel bioreactor was proposed based on a strategy of lateral root bridging by utilizing mesh as a hindrance, called "mesh hindrance mist trickling bioreactor (MHMTB)". Significant improvements of dry weight and L-DOPA production by using MHMTB were 1.8 and 2.2-folds, respectively, higher than those in the control run without the mesh hindrance within the root bed.

Bioreactors↗
PubMed1999

Diurnal variations in hydraulic conductivity and root pressure can be correlated with the expression of putative aquaporins in the roots of lotus japonicus

The hydraulic conductivity of excised roots (Lp(r)) of the legume Lotus japonicus (Regel) K. Larsen grown in mist (aeroponic) and sand cultures, was found to vary over a 5-fold range during a day/night cycle. This behaviour was seen when Lp(r) was measured in roots exuding, either under root pressure (osmotic driving force), or under an applied hydrostatic pressure of 0.4 MPa which produced a rate of water flow similar to that in a transpiring plant. A similar daily pattern of variation was seen in plants grown in natural daylight or in controlled-environment rooms, in plants transpiring at ambient rates or at greatly reduced rates, and in plants grown in either aeroponic or sand culture. When detached root systems were connected to a root pressure probe, a marked diurnal variation was seen in the root pressure generated. After excision, this circadian rhythm continued for some days. The hydraulic conductivity of the plasma membrane of individual root cells was measured during the diurnal cycle using a cell pressure probe. Measurements were made on the first four cell layers of the cortex, but no evidence of any diurnal fluctuation could be found. It was concluded that the conductance of membranes of endodermal and stelar cells may be responsible for the observed diurnal rhythm in root Lp(r). When mRNAs from roots were probed with cDNA from the Arabidopsis aquaporin AthPIP1a gene, an abundant transcript was found to vary in abundance diurnally under high-stringency conditions. The pattern of fluctuations resembled closely the diurnal pattern of variation in root Lp(r). The plasma membranes of root cells were found to contain an abundant hydrophobic protein with a molecular weight of about 31 kDa which cross-reacted strongly to an antibody raised against the evolutionarily conserved N-terminal amino acid sequence of AthPIP1a.

Journal Article↗
PubMed2005

Improved outcome with composite graft versus homograft root replacement for children with aortic root aneurysms.

OBJECTIVE: Review of surgical repair of aortic root aneurysms using composite graft or homograft in children. METHODS: A consecutive series of 34 children (mean age 10.8+/-5.4 years) who underwent elective aortic root replacement using composite graft or homograft from 1987 to 2003 (mean follow-up 5.7+/-3.7 years). RESULTS: Preoperatively, the aortic annulus and aortic root average z-scores were 4.1+/-2.2 and 9.4+/-4.7, respectively. Composite graft root replacement was performed in 22 patients, and cryopreserved aortic homograft root replacement in 12 patients. There was one perioperative death in the homograft group due to sudden cardiovascular collapse. There was one late death in the composite graft group due to acute aortic dissection, and two late deaths in the homograft root replacement group, one at 7 months postoperatively due to coronary artery thrombosis and one due to severe chronic myocardial dysfunction 5 years postoperatively. One patient who initially had a homograft died due to mechanical valve thrombosis following reoperative composite graft replacement. Five patients had reoperations at a median of 7.1 years after initial surgery. One patient in the composite graft group underwent arch replacement. There were no graft related reoperations after composite graft root replacement, but 4 patients in the homograft group had reoperative composite graft replacement. Predictors of reoperation included age at surgery, lower weight, and longer ICU time (P<0.05). CONCLUSIONS: In children with aortic root aneurysms, reoperation is more common after homograft root replacement than composite graft replacement. Composite graft root replacement provides more stable repair of the aortic root.

Adolescent↗
PubMed1997

Programmed cell death in the root cortex of soybean root necrosis mutants.

The soybean root necrosis (rn) mutation causes a progressive browning of the root soon after germination that is associated with accumulation of phytoalexins and pathogenesis-related proteins and an increased tolerance to root-borne infection by the fungal pathogen, Phytophthora sojae. Grafting and decapitation experiments indicate that the rn phenotype is root-autonomous at the macroscopic level. However, the onset and severity of browning was modulated in intact plants by exposure to light, as was the extent of lateral root formation, suggesting that both lateral roots and the rn phenotype could be directly or indirectly controlled by similar shoot-derived factors. Browning first occurs in differentiated inner cortical cells adjacent to the stele and is preceded by a wave of autofluorescence that emanates from cortical cells opposite the xylem poles and spreads across the cortex. Before any visible changes in autofluorescence or browning, fragmented DNA was detected by TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling) in small clusters of inner cortical cells that subsequently could be distinguished cytologically from neighboring cells throughout rn root development. Inner cortical cells overlying lateral root primordia in either Rn or rn plants also were stained by TUNEL. Features commonly observed in animal cell apoptosis were confirmed by electron microscopy but, surprisingly, cells with a necrotic morphology were detected alongside apoptotic cells in the cortex of rn roots when TUNEL-positive cells were first observed. The two morphologies may represent different stages of a common pathway for programmed cell death (pcd) in plant roots, or two separate pathways of pcd could be involved. The phenotype of rn plants suggests that the Rn gene could either negatively regulate cortical cell death or be required for cortical cell survival. The possibility of a mechanistic link between cortical cell death in rn plants and during lateral root emergence is discussed.

Apoptosis↗
PubMed1992

Leaf water status and root system water flux of shortleaf pine (Pinus echinata Mill.) seedlings in relation to new root growth after transplanting.

Water relations and root growth of shortleaf pine (Pinus echinata Mill.) were studied four weeks after seedlings from a half-sib family had been transplanted to one of three regimes of soil water availability at a root zone temperature of either 15 or 20 degrees C. About one-third of the variation in new root growth was explained by the root zone environment. The interaction between root zone temperature and soil water availability accounted for 10% of the variation in new root growth. In the most favorable root environment, new roots averaged 620 mm(2) of projected surface area. Leaf water potential increased exponentially with new root projected surface area, becoming constant at about 300 mm(2). Leaf conductance and root system water flux increased linearly with new root growth.

Journal Article↗
PubMed1998

In vitro effects of Laccaria bicolor S238 N and Pseudomonas fluorescens strain BBc6 on rooting of de-rooted shoot hypocotyls of Norway spruce.

The ectomycorrhizal fungus Laccaria bicolor S238 N and the bacterium Pseudomonas fluorescens BBc6 were used separately and in combination to induce in vitro rooting of de-rooted shoot hypocotyls of Norway spruce (Picea abies (L.) Karst.). When the culture medium was supplemented with tryptophan, a precursor of indole-3-acetic acid (IAA) synthesis, the presence of the ectomycorrhizal fungus increased the percentage of hypocotyls forming roots; furthermore, both the fungal and bacterial inoculations enhanced the number of roots formed per rooted hypocotyl. Similar results were obtained by adding exogenous IAA (5 and 10 &mgr;M) to the rooting medium. After the rooting phase, the fungal inoculation enhanced adventitious root elongation and branching as well as the aerial growth of the cuttings. Pseudomonas fluorescens BBc6 had no effect on these parameters. The production of IAA by pure cultures of L. bicolor S238 N and P. fluorescens BBc6 was estimated by immunochemical analysis using specific anti-IAA antibodies. Both L. bicolor S238 N and P. fluorescens BBc6 synthesized IAA in pure culture and synthesis was stimulated in the presence of tryptophan. Thus, the effect of the fungus in stimulating adventitious root formation and subsequent elongation and branching can be attributed, at least partially, to the synthesis of IAA by the fungus. The finding that P. fluorescens BBc6 had no effect on root elongation and branching although it produced IAA suggests that either IAA was not the only parameter involved in the stimulation of these processes by L. bicolor S238 N or the bacterium produced other compounds that counteracted the stimulatory effects of IAA on root elongation and branching.

Journal Article↗